BSA Owners' Club Workshop Discussions

Hi Folks,
   
  The C15 is still not starting since my last post.  Any bright insights?

  The plug is sparking when out of the port.  I can see it.
  I've opened the carb and unblocked the jets
  The fuel has been in the can for a few weeks but it smells fresh.
  The plug is wet with fuel after kicking over. 
  The engine hasn't been open since it last ran, so timing shouldn't be an issue. 
 
  I thought that I might buy some Easy Start and some super fresh fuel before I try again. 

  BR,  Ian

   

Before someone asks, not so much as a kick or a spluter.
The battery was freshly charged.
Compression shouldn't have changed but it is making the right sort of noises on kicking over.   

If the plug gets went it suggests fuel is getting that far. I use easy start if there doen't seem to be any fuel getting through as that usually confirms you're getting a spark at approximately the right time.

I'll buy a can

It is frustrating!

My chief problems have been fuel degredation and sludging up of airways/jets with machines left standing with modern E petrol sitting in them.

It goes without saying that you know that your timing is correct (if points they must be clean and gapped correctly with a working condenser).
LT connections on coil must be clean and tight.  Plain HT copper core and non-suppressed HT cap
New plug.

What's your starting procedure/whar are you doing to start it? Ticking the carb, choke etc etc? You might be flooding it perhaps?

Procedure wise,  tickle the carb till fuel starts to come out of the button.  Ignition on.  Check the current on the gauge, needle twitching.  Turn the engine over on the kick start until I reach compression, then let the lever return and kick. 

  If fresh fuel and Easystart doesn't work I might be checking the points, but I was hoping to avoid this.  They shouldn't have changed anyway. 

You may wish just to change spark plug ,it may be sparking but check isn't spackling from electrode to earth pin , not sparking from inside the ceramic, just a thought Roy

OK,  Easy Start, Fresh fuel, new spark plug, then timing

Spend 3 quid on a ht neon tester.
This goes onto the plug and ht lead onto the tester.
At least you can see if it's sparking under compression.
Dare we assume the ignition timing is correct ?
Has it ever run in your possession ?

Have you tried taking it just past top dead centre/easing it over compression before you kick?

I'm checking out the spark testers but they seem to use the bullet connector rather than screw unfortunately: https://www.ebay.co.uk/itm/111987068352?itmmeta=01J3WZKJ3ZTD7XJ60HKPG0WD5Y&hash=item1a12f30dc0:g:GxkAAOSw3ZxaEule&itmprp=enc%3AAQAJAAAA8CIcgRXfyCkGf%2FLPpgYwHJlQR3eXKQLb4j3gVYTAcIgc%2Bi63gy02WXopTkIfHmHWBxosqSzU0NVqKdyp5BhnFNvs73qzRf5i1vxCmW9T5Tvr3FXVkC7qHXyji7T2tvrNXZJVu99cjsliH8idCq2%2BnFJ7hl%2FbSWl6bnBo00rblmYCWOJBMhop8%2Fs%2FvQ%2BTVr8U1jKMDKNvzjsFYZQpCDppNrroQ9bQT%2BSHs4P2uVTRySSlzCd82YTmmYhN5LxOFHjqvysiQ%2B2eq91fxnWjdVNRjyQEfspHbBCWEG77ihLAjWiYz4WBaGbjuAuOABDvdRvsiw%3D%3D%7Ctkp%3ABFBMiKLOn59k&edge=1

I tried kicking from before and after TDC, but no result.  This would be easier if I have a valve lifter.  A dab of throttle didn't help either. 

I feel I am repeating myself a little, but, just to be clear, the bike ran OK prior to replacing the loom.  That is all I have done.  I have volts on the coil, although it is a little low, maybe 4 to 5 V rather than the full 6, but I am seeing a spark on the plug when it is out of the engine, on the HT lead.  I've unblocked the jets and I'm seeing fuel on the plug, so there is fuel getting into the cylinder. 

If the voltage to the coil is low that will give you a weak spark which can be blown out under compression. Run a wire from the battery direct to the coil then try.

Okay, good plan, I'll do that.  Thanks!

Hi,
Totally unrelated to a C15, but I recently had exactly the same problem with an old Suffolk engine.
Wet plug, big fat blue spark but no go.
Just about to throw the towel in when I swapped the Champion plug for an NGK.
Fired first pull!

My pal replaced the loom on his Tiger Cub - and put the wires to the three position ignition switch on incorrectly.  C15 has same switch with emergency position...  Just a thought.

I think that, if the ignition switch was incorrectly wired, I would have no spark.   That said the resistance of the switch and the ammeter could have an effect.   

Last night, I topped up the charge in the battery and kicked it over.  It coughed once and then no more. So I left the battery on charge over night.  But no joy, no cough nothing. 

SO, new plug, new spark lead, new battery all seem good options.

   This is the sad point where I throw money at it until it starts working.  Always sad to buy new parts only to see it have no effect. 

BTW the plug is already a new NKG (B8ES)  . I wonder what the odds are that it might be faulty?  I wish I had the old one., but I swapped them months ago. Any suggestions as to the best plugs to use gratefully received.

Okay, I dug around and found the old plug, which happens to be iridium, but it didn't have any effect

Two heads are better than one. Maybe there's a member in your area who could pop over and help

So, before the loom change all fine and running
Now , after loom change , not running.
Obviously retrace every step , does every other function work correctly ? Go over every single function.
If it is only this ignition area that is defective then at least its narrowed to a manageable area
You have the 2 separate  areas of supplying the ignition coil with electricity,
Normal on and EMG
Concentrate on the normal on path 1st and get it running there

I would try a jury-rigged live direct from the battery to the coil (disconnect the loom wire from the coil). This will make sure you're getting the full voltage there. 4-5 volts is very low especially with a fully charged battery.

With regards to spark plugs. I read recently that there are a lot of counterfeit NGK plugs around, especially on EBay.
The advice is to source plugs from a known a reputable place.

Very true, although there is a page on the Net giving the signs to look out for with counterfeit plugs.
Surely the OP has a spare plug (or one from another bike) that he could try in the meantime? As Mr Soady says above, a simple flying lead wired from battery to the coil feed would check the ign switch and associated wiring.

You mentioned sometime last month, that you only had 4 volts on the coil.  This should be over 6.5v if your battery is Ok.   So can you trace all the wiring from the battery to the coil, to see where you are loosing the 2 volts..?    If the battery is only 4v then try starting when you have a battery charger connected.

Isn't an NKG (B8ES) a bit hot. I used to use this in a Velocette Venom with rather a high compression ration. I would have thought a softer B6.....or similar would be a better option.

Maybe you are right, but it shouldn't stop the bike starting should it? The bike came with the B8 iridium plug and it was running before. 

BTW  the sump was dry too.  We checked that this evening. 

I'd thoroughly check the earth connections. I'd also advise that you get someone to check the volts on the coil while it's being kicked (Dad had a Mini with an earth fault; it lost all power to the coil when being cranked). This is reading like an earth fault to me. Low voltage on the coil hints at a resistance somewhere in the system.

Yeah,  I measured the resistance, battery to the coil and it was around 1 ohm on both sides, so, could be worse.  We tried kicking in the emergency position of the switch too, but no joy even though we had sparks in both positions. 

Weirdly the lights won't work when powered from the battery, only if I substitute a bench power supply, so maybe the battery is a little tired.  Any recommendations of a good battery to go for? 

I've been looking at the wiring diagrams. Does anyone know which pins connect together on the ignition switch?  Not easy to understand in the diagram, either Hayne or Rupert Ratio.
The loom is clearly labelled as being up to 1963, but I wonder if there might have been any variations. 

My thought was to bypass the ignition switch and ammeter but I want to properly understand what needs to connect to what before I pitch in. 

So you get a spark in both positions , good
Various posts seem to indicate the battery voltage is weak , try starting it with the battery charger connected and switched on , the ignition (if you're on 6v still) , will pull about 4 amps which will quickly kill a tired battery.
Battery , look at Tayna batteries , good prices and delivery.

Okay, I have ordered a Motobatt from Tanya, thanks !

Quote from: iansoady on 01 Aug, 2024, 10:17
I would try a jury-rigged live direct from the battery to the coil (disconnect the loom wire from the coil). This will make sure you're getting the full voltage there. 4-5 volts is very low especially with a fully charged battery.

Have you done this simple thing just to get it running to prove that everything else is ok?

Yes, I had tried that but without any joy.

I've also tried kicking over with the battery charger (4A) connected, but the battery quickly dropped to 4V. 

Buzzing out the loom against the diagram in Haynes hasn't revealed anything.

The ignition switch buzzes out OK too.

  Maybe I will be waiting for the new battery.

Does the metal case of the coil count as a connection to + ?  Right now I have 10 ohms between the can and battery +, so, maybe a link wire to the battery here would help? 

It definitely sounds as though either the battery is dead - your new one should eliminate this possibility - or that there is a partial short circuit somewhere draining it. When you tried my suggestion did you remove all other connections to the battery and coil?

The 10 ohms between coil casing and earth is by the way - it won't really affect anything. Have you checked what the current is between battery & coil when the points are (a) open - should be zero - and (b) closed - should be no more than an amp or so.

The outer can or body of the coil should not connect to any of the coil connections.
Either the 2 small primary connections or the central ht connection.
Basically, the voltage , negative volts , go battery , switch , coil neg , through coil primary , out coil pos to points , along the points wire to the points and to earth at the points.
Making and breaking points create and destroy the magnetism in the coil.
The dying or collapsing magnetism creates a high voltage , 12 or 15000 volts in the HT side of the coil.
The spark whizzes along the htlead through the plug and back to earth through the engine to chassis to battery earth positive.
It doesn't rely on the coil can or body.

Thanks for all of that.

  With the coil connected and the ignition on the ammeter indicates around 2A, and the battery voltage rapidly drops below 4V.  If I disconnect the col terminal the voltage goes straight back to 6V.

  I'll try out the bypass lead which I made up again. 

Just to confirm.  I measured the current through the coil and it is 2A on my multimeter, with the points closed. 

What is slightly odd is I am supplementing the battery with the battery charger, which is rated for 4A, but the battery is still sagging. 

Resistance between the coil and ground shows open circuit with the point open and closed circuit with them closed, as you might expect.

   It all seems to be pointing in the direction of a duff battery.

I think youve just proved it.
Ignition on and points closed (so the battery goes to earth via coil primary and points).
Is tantamount to a straight short to earth.
Obviously as engine rotates and points make and break the short to earth is momentary.
How long are you leaving it connected before voltage drops to 4v ?
Get your new battery on and see how you go
as a matter of interest , how old is the current battery??

a 6 v coil is about a couple of ohms across the 2 primary connections + and - (remove everything else when checking)
and from 1 of these primary connections to down inside the HT connection is around 4k ohms give or take

Sorry I have no idea how old the cyclones are as they came with the bike. 

A typical bike 6v battery would be about 8 amp-hour rating, in other words will supply 6 amps for an hour (or 2 for 3 hours). Definitely the battery from the readings you've provided.

Sorry to hear of the ongoing problems.  Lots of things you tell us seem to make no sense.
 
For example... The coil case to ground being 10 ohms, is neither grounded nor open circuit, but somewhere in the middle...  Almost like an internal fault to ground, caused by a partial contact to the coil windings.   
I know this won't help much, but my R.E. Bullet coil case is not connected to ground, even though it is clamped to the rear mudguard.!

The other strange thing is that you say the battery voltage sags even with a Battery Charger fitted, and that the lights go dim from just the battery.  Maybe as the voltage is going to 4v, that could suggest only two cells of your battery are good.

Maybe a push down a hill by two strong lads, whilst in second gear, would get it going..  Best of luck..

Yep.  I am confused too.  The more I find out the less I seem to know. 

I think the coil case to frame resistance is a red herring. It's probably just the combination of paint and rust. But anyway doesn't matter as explained earlier.

Well, I'll update you all when the new battery arrives next week.  I won't do any more on it until then.  Just cross everything.

Where are you getting your battery from? Tayna usually deliver the next working day. The last one I bought, a few weeks ago, was ordered late Saturday afternoon and arrived at 10 am on Monday. And at a brilliant price.

Tayna are excellent. When I ordered a battery from them recently by physical size, a note flashed up on the screen saying that this battery was available cheaper (from them) in a different make. And it was, by about £8.

It was late on Sat that I ordered, so, hopefully it was shipped today and will be with me tomorrow.

I note too, that I found today that I could get an 8AH Cyclone to replace the two 2.5AH Cyclones which I have wired in parallel, but I will try out the Motobatt before I even think about going in that direction. 

Okay.  New Battery fitted. 5V on coil now.  Still won't start. 

I'll try some fresh fuel at the weekend, but, if Easy start doesn't help I don't expect fresh fuel will.

   Does anyone want to buy a bike? 

What part of the world are you in?

Quote from: Barnsey on 06 Aug, 2024, 18:19
Okay.  New Battery fitted. 5V on coil now.  Still won't start.   

That's still low. Have you tried the previously-mentioned flying lead straight off the battery?

As said 5volt at coil to low the coil is not working at full capacity. A fully charged 6 volt battery should give 7.5 volts.

OK. I did try the flying lead previously, but I'll try it again with the new battery.  I'll repeat some of the other basic checks too. 

And, for the record, I am in Clanfield, near Waterlooville, in Hampshire.

I charged the battery up to 6.5V and added a wire directly from the battery negative to the coil.   I had 5 V on the coil.   Still not starting

However looking at the circuit diagram, in normal running, the positive return is through the engine to the frame, not through the black wire.  Measuring this path gave 3 ohms.  SO I am tempted to add an extra ground wire from the frame to the points cover. 

If your bike is pos earth then you're correct, as I indicated in an earlier post the HT voltage circuit is through the ht lead , cap , plug , engine to earth , and the pos earth lead to the battery.
If you have 3 ohms from battery earth wire to the frame or engine , then obviously correct that.
But have you checked the quality and strength and colour of the spark?
Get an old plug , bend open the electrode to 3/16 or 1/4 inch gap , lay it on the head and kick bike over , does it give a good strong blue crack of a spark ?
If not , unscrew the ht cap and lay the lead only on the head and kick over , does that give you a 1/4" spark.

I always have a dedicated earth wire to the engine as otherwise you're depending on bolts going through paint, rust etc. I also fit earth wires to tail light and headlamp for the same reason.

Annoyingly I trashed my last ring terminal !  More on order.  Let's pray that they will arrive tomorrow so that I can do the job over the weekend.

I found the original loom which I had tucked away, and the previous owner had certainly added a couple of extra ground wires.  Maybe this was an issue.

New ring terminals arrived yesterday, so I fitted a new grounding wired between the rectifier bolt and one of the rocker cover nuts. 

Now showing 5.5 V on the coil.  Still losing a volt as the battery is 6.5V.   Fresh fuel added plus a squirt of easy start but not so much as a splutter. 

Strange , you do get sparks across the plug ? I think you said you do.
So back to basics , decent compression , valves opening and closing , valve clearances of course.
Dare I assume the spark is in the right place  and timing not slipped.

Yes I had a spark.  I didn't get time to check it today, but I will. Family life means I get the odd half hour here and there. 

Since the bike was running prior to fitting the loom, timing and compression shouldn't be issues but I think I am at the point that I need to start checking these things too. 

That said I don't think compression is an issue.  It is much harder to kick over with the plug in than out and it makes the right sort of chuff chuff noises. 

  I will also look at some of the other suggestions.  As I say, family & work prevent me doing everything in one session, but I value all suggestions and will get around to trying everything. 

BTW...

     I kicked it over with the plug out. There is a regular spark on the plug, even turning over slowly on the kickstart by hand.  So I don't think the coil voltage is an issue now. 
The plug was wet when I took it out.
The previous owner, helpfully, put a timing mark on the points in red paint, and it hasn't moved. 
I checked the wiring on the ignition switch and it is entirely consistent with the wiring diagram for an early bike.
Buzzing out the switch sowed it to be correct.

   Ian

Silly question, I know, but I am new to old Brit Bikes,  can I flood the bike and keep it from starting through over tickling it?  My guess is no, as the carb bow will be lower than the manifold if the designer had any sense. 

I generally tickle until I get fuel coming out of the overflow in the button, and I am assuming this is the correct thing to do. 

My ss80 will not start if I tickle it too much and use the choke.
Then I have to take the choke off , twistgrip WIDE open and start kicking , it'll go then , roughly then clears.
Are you tickling till floods and choke as well ?
Different times of year demand different amounts of tickle and choke !!

No choke on my bike, only tickler, but I will try tickling it a little less.   I have tried with a little throttle too, but no result. 

Have you tried no tickle? I'd want to start off lean (no tickle) and richen it progressively until it fires. That way you can avoid flooding it and figure out whats right rather than hoping you randomly hit the spot without flooding it (if that makes sense???).
Start with a dry plug and kick the bike over several times with the plug out and the throttle wide open to clear it.

Good plan!  I'll try that out and report back later today!  Thanks

Good luck. Take your time. There's some logic in it somewhere!

You say the plug is wet which definitely suggests over-tickling. The level in the float chamber can easily get so high that neat fuel is dripping into the inlet tract when tickled. I'd agree with KernowPete2.

My Ossa MAR is a pig to start at the start of a trial.  It has a Monobloc carb and requires the tickler to be pressed a further 20 seconds after the fuel comes out, to put some fuel into the crankcase.   Once it has started that way in the morning, it fires up perfectly every time with no tickle, for the rest of the day.   I have some bikes with the Mikuni carbs, and they are simplicity themselves, with just the richening plunger raised.
I think Amal didn't really do a good job for cold starts, even the Villiers carbs had a nifty sliding choke on the air filter, which was very efficient.

Sorry if I am not a carb connoisseur but I was recommenced to replaced the stock carb with the larger Amal with choke,  but, to my annoyance, it didn't fit between the engine and the air box on my stock bike. SO it got sent back.

  If anyone can recommend a carb which is reliable and cheap and will fit a stock bike then I am all ears.

Right now I am being distrated by a leak in the fuel tap.

This is a side issue, so I will start a new thread.   

Lots of excellent advice here. I hope you get time to take it all on board, but you seem to have bypassed some of the suggestions.
Could I ask if your 5 volts at the coil is with the points open or closed?
Just laying the plug on the head won't tell you anything very much. You need to do a spark gap test, as already suggested.
Sounds like you're flooding it. Heat the spark plug, and try it again.

Yep,  5 V with the points closed.  Holding the points open with a cable tie gives me the full voltage.  It is still losing a volt somewhere, probably in the switch.  I can certainly try bypassing the switch with a negative wire direct to the coil.   Should I really need the full 6V?

  Flooding?   Yes, I was in the process of looking at this when the fuel leak distracted me.  Kick it over with the plug out, to clear the surplus fuel and heat the plug. 

   All good stuff, and thanks to all.

     I must say how I am surprised that I get replies at all times of the day and night. 

        Now, I am away on holiday for a few days so you might not hear from me until next weekend.

It's been a while,due to holidays and stuff but a new update.

  I bought a spark tester, which I had to tweek with my dremel to make it fit, but it showed that I was getting a spark when the plug is in the cylinder.

   I tickled the carb, which overran as usual, due to the float sticking, so a tap with a hammer fixed that. 

    Then I took the plug out and spun it over a couple of times to clear any surplus fuel. 

   Plug back in and kick.  One promising cough but that was it.   

   Next I will try pre-heating the plug a bit before kicking, as someone suggested, and I am still seeing 5.5 volts on the coil, so I will look at getting teh full 6V plus. 

Attempt no 2.  Battery charged up to 7V.  I bypassed the ammeter giving 5.7 V at the coil.

  Tickled the carb,  It overruns again, so a tap with the hammer, to unstick the float. 

   Plug out.  kick over.  Heat the plug with my blow torch.  Plug back in.   Kick.  Not a sausage.  No cough, nothing. 

Petrol off
Wide open throttle
Kick to clear flooding ??

Okay.  I'll try that, although I'd have thought that kicking it over with the plug out would do the same thing. 

Sorry to hear of the ongoing start problems.  I recently fired up a C15, and my method was as follows...

Tickle until fuel spills from the plunger.
Kick until at the top of the compression stroke, as near tdc as possible, then release the kickstarter to the top.
Twist grip just a bit open... 1/4..
Then Kick down, and continue forward as far as possible, at the bottom of the stroke.

Best of luck, or find a steep hill to bump start it in 3rd or 2nd..

My ss80 needs to go just over tdc with the kick start (I use the ammeter to show points open)
And then a good full swing down

Good tip about the ammeter. I'll try that.

To be fair a C15 shouldn't really need the "big single" starting method, and to kick it over so many times without a cough suggests there's something more wrong than just starting technique. ???

IT LIVES !!!!!

Those last couple of bits of advice did the trick!  It started and ticked over quite happily but weed oil all over the floor.  Luckily it turned out to be just a disconnected return pipe.  I'll fix that later. 

   The other thing I did was to reconnect the ammeter in the reverse polarity so that it shows negative as discharge and positive as charge.  Is there any crazy way in which this might have had an effect? 

  It seems odd that something so simple would have been the fix but I suspect that there were various small things along the way which all had to be right.     Back in the day every lad would have known how to start an old bike but nowadays it seems to be a dark art!

We will see if it will start again next weekend!!

I know you have a spark but how good is it. Is it being snuffed out under compresion. Get an old spark plug and bend back the side electrode until you have big gap something like 3/8 inch at least the spark should be able to jump that. If it does then your problem is elsewhere.

Now that is a good suggestion!  I have a spare spark plug so I will try that out. 

At least its running now , you can fiddle with the other bits later
Get used to different ways  it likes to start , each of my bike's have a different technique

The saga continues.  Back to not starting today.
I opened the carburetor and had another go at it with the wet and dry to stop the float jamming.
Fresh fuel, charge battery and kick over.  It pops a bit, which I guess is progress, but it didn't start. 
5.4 V on the coil.
Adding a wire direct from battery to coil gives 5.8V on the coil but still no go. 

Does the coil voltage not seem like a bit of a red herring especiallly as you know you have carb issues and it sounded from previous posts that it might have been getting flooded? What model of carb do you have?

I am sure you are right about the electrics. The spark tester indicates a healthy spark anyway.  I am back to using the iridium plug which at least gives a chug.  I got nothing with the BK.

The carburetor is the stock Amal item.  Someone once recommended getting a new one, but the stock Amal costs a packet!  I did try a later carb but it was too big to fit in the space. Any suggestions welcome.

Since my cleaning work the carburettor is no longer flooding. Previously I have  fuel pouring out of the tickler when the float stuck.

Look at the tickler button body that's screwed into the top of the float chamber.
You should not have a water under the body where it screws down onto the float chamber.

Agreed. No washer fitted.   I might double check the jets tomorrow, although I have already cleaned them once. 

Exactly what position should the engine be in when I kick?  I manged to inch it around to TDC with the point open before kicking, but no joy. 

Should my carb be a 375 or 376? I am investigating rebuild kits

C15 I'm sure 375

Using the kick start pedal , bring it up to tdc
Ease it over tdc just.
Then ignition on and good kick
Try wider throttle if you feel too rich

Is there a chance the clutch could be slipping? It should be easy to identify by feel as you kick it.

I'm not aware of any slipping. I'm not entirely sure of my technique tho'.

A carburettor kit can be bought for around £36 so not too bad.  Are there any wrinkles to be aware of if I do the job myself?  Or might I be better off to farm it out to an expert?   

Oooh Heck, Thought it was solved...   I have a C11 which is sometimes difficult to start, and have put the cause down to it wet-sumping.   If left standing for a month, it fills the crankcase and the chaincase from the oil tank.   The additional crankcase pressure. and oil prevents an easy start.   It also has a stupid shock absorber on the primary chain drive, which doesn't help with the kick momentum.

You have to follow a technique to ensure a start, I've just gone into the shed and started my c15.
Up to tdc with the kick start.
Release kick start up to the top of its travel ready to swing again.
Using kickstart , ease it just over tdc , release ks
Ignition on , throttle set , good firm swing with the pedal , away she went.
I had a tiny press of the tickler until my finger was just wet.
No choke
Away.

But the suggestion of wet jumping is very valid , given the time it has not been started.
Slacken the 4 nuts on the sump plate , drain oil out and pour it back into oil tank
Nip up nuts
Try to start it given above process

I don't think that it has been wet sumping.  My mate and I checked for that once before by taking the drain plug out of the sump, (do I REALLY need to remove the strainer plate?).   No slurping noises either. 

I am tempted to ask my wife to give a squirt of Easy Start while I kick.   If that works it might prove that there is an issue with the carb. 

I might check the jets again too.  I've already cleaned them once, but how long can it take for them to block up with standing? 

   BR,  Ian 

you don't need to remove the sump plate or filter - just ease them off and let it (if any) dribble out

I got it running again:
1/ Carb and check the main jet. Spilling yellow petrol everywhere
2/ Reassemble.
3/ Preheat plug with blow torch.
4/ Tickle
5/ Kick over with switches off and throttle wide.
6/ Switches on and kick over again. 

  I stopped the engine when the carb started to leak fuel.

  I'm strongly tempted to buy a service kit for the carb. 

    I'f I can't get to a point that it will start on demand going on trips out might get a bit iffy!!

 

Plug should be N5 or equivalent
Where is the leak actually coming from??
Is it the bottom jet block to main body ? If so may need the main body face truing and cleaning up, those faces often get damaged

Yes it was.  I tightened it up a bit but I think it might benefit from a new fibre washer

thats a regular place to leak Burlen do those fibre washers , but when you get them , check the quality of the faces the bottom of my main body was quite pocked and needed a careful facing square and decent - now dry

https://amalcarb.co.uk/monobloc-series/375-series/gaskets/gasket-sets.html     about 6 quid plus post

if you're disturbing the carb off the head, have a you the fibre plate between the head and the carb , must have that
and if you dont know the history off the needle jet or needle then consider them as mentioned earlier in 1 of my posts to you
check also the truth of the carb flange face - -use a surface plate of piece of glass to ensure it is really flat - do NOT tighten the 2 flange nuts up stupidly tight - just enough
you should be there

Thanks!  They actually do a more comprehensive kit with the needles and jets too for around £36. I just need to figure out which jets. Now..  wheres my manual? 

Or , as suggested speak to burlen.
I credibly helpful and knowledgeable

Carbs sitting unused for a while with modern fuel (E10) will fur up their pilot jets and cause a lot of the symptoms you describe.  It can also damage the float needle seat (depending on the material in yours).  Trouble shooting for this was a PITA as I found it hard to believe that something so simple could cause the problem, similar to just dirty fuel.  By the time tank flushed, filters cleaned, spark plugs in/out shake it all about it was quite frustrating.
Depending on your model are these your settings?:
7/8" Bore
140 Main Jet
105 Needle Jet
25 Pilot Jet
4.0 Slide
A genuine service kit would be an excellent idea.

Is it definitely leaking out of the tickler? If it's leaking out of the joint face then the pilot jet might not be pulling in fuel from the bowl. Assuming it's a concentric carb. Both bikes I have have concentric carbs and I've had to flatten both float bowl joint faces on a piece of glass with fine wet and dry to stop them leaking.

Just saw my above post. Not 7/8" bore
Much more like 626 (26mm) ?

I am not an Amal connoisseur but I understand that the carburettor which I have fitted is the original Monoblock and they cost a packet to replace.  The bell mouth on the concentric is bigger.  Has anyone managed to fit the concentric without having to enlarge the hole in the air box? 

The inlets should be similar size.
Just unscrew the bell mouth.

Actually I am sure the concentric had a larger choke.  Maybe the who thing was completely the wrong size.  Hhhmmm!?    I've found the correct jet sizes so I reckon I will buy a service kit for the carb I have, in the first instance, and then go from there.   

Hi, 

    I've been doing various odd jobs on the bike for a few weeks, during the cold weather.  Now I am back to starting it and I am back to the drawing board.  Lots of straining and cursing, but when it does eventually start it does so really easily.  I am reviewing the notes in this thread,  but I wanted to push this back up the list in case anybody else has any better ideas.  .

   BR,  Ian

I made a perspex cover for the carburettor today, and, although it cracked straight away, it showed me what I wanted to know. The bowl is overfilling by maybe a quarter inch.  In fact it may not be shutting off properly at all but flooding the engine.  I noticed fuel in the air filter hose.  A total pain because the petrol strips the paint off of anything it touches. 

 So.  Where to start?  There seems to be no float adjustment. DO I need a new float or a new needle ?   

BTW  there are no shims under the banjo, so the only adjustment is upward.

I've ordered a new floatkit of the stay-up ethanol proof variety.We will see if this helps at all.   

Hi,

The new float and needle may do the trick but ultimately a new carb may be the best solution as the inner air/fuel ways will be worn and corroded.  7/8" is 22mm

Dave.

Well...  That was the start of the sad saga.  A mate advised me to buy a new carb, but monoblocks are expensive, so I ordered a concentric, but it didn't fit in the space available.  If anyone can advise so that I can buy exactly the right one this time it would be appreciated.  I don't want to be modifying the airbox to make it fit.

Hi,

I seen concentric carbs on C15s but cannot say for sure if the air box was modified.  Someone on this Forum must have done it. I have just fitted a 22mm Mikuni to a '62 C15 and it work well. A bit of a fiddle getting it on and it will need a bespoke bit of rubber to connect it.
Have look on Motocarb.

Dave.

Thanks Dave!  Mikuni carbs are not a cheap option either, but I will bear it in mind. 

  My dilemma is that that, even after 2 years of work, I haven't ridden the bike yet.  I'd prefer to keep it cheap until I have had a test ride. I don't want to spend the best part of £1000 on posh carb, electronic ignition etc, and then decide that it isn't for me and sell it.   However, one way or another I need it to start and run.  Keep watching this space! 

Looking at the number of pages on this subject , 7 or 8 I think, is is worth rebooting as to what you have or don't have, eg sparks and fuel and compression etc.
I have 2 C15s and each is different procedure to start

Okay.  I had a thought.  I filled the carb bowl half full and then turned of the fuel tap.  Kick over and it started on the second kick, but then stopped after a couple of seconds.  I thought that I was onto something, so I tried again and it stubbornly refused to start at all.  I topped up the carb a little, to around 3/4 but it still wouldn't start. 

  Read what you will into that! 

So you have a spark at least.
Looks fuel related.
1 of my c15s needs choke to start , the other , only a gentle tickle.

To check if a spark is really present while kicking unsuccessfully, I use a stroboscopic lamp.
No flash, no spark.

My lazy k2f gives sparks when the plug is outside.
But the stroboscopic lamp shows no spark when the plugs are installed.

Thor spark system about to be installed. ::)

I definitely have a spark.  I tried starting with a squirt of Easy Start this morning and the dammed thing kicked back and nearly took my foot off.  How do you avoid that or is it just an occupational hazard?  It still didn't start tho'

Any 4 stroke needs a certain style of starting.
Up to compression and ease over the top , then a forceful kick.
No other style will work
Both of mine will give a little kick , but this is resolved (or greatly reduced)if you follow the above routine
The correct placing of the kick start lever is vital to effect the correct swing at each stage

Okay, I have rebuilt the carb for a second time, with ultrasound cleaning.  No obvious corrosion. Clear jets.
I also bought some fresh fuel and have given the battery a good charge up.  Now I just need the new float to arrive before I try it again.

New float fitted.  The fuel level in the carb is good and the new float doesn't stick like the old one. 
Battery charged and new fuel. 

I thought I had cracked it this time but it wasn't to be.  Still no go.   

Thinking through my options.  Next I reckon I will try tweeking the timing a little.  If that achieves nothing I'll look at the richness on the carb. 

Hi,

After trying to get it started using the tickler, what is the plug like?  Is it wet with fuel or completely dry?

Dave.

In these circumstances I usually try a squirt or two of easy start. If it starts and reuns for a few seconds this shows the problem is carburation. If it doesn't then I'd be looking at the ignition system.

Well,  I tried the squirt of Easy Start, but it didn't help.  Maybe because I couldn't squirt and kick at the same time.  I had to squirt and then rush around the bike in order to kick.  Maybe I can get my Missus to squirt while I kick later on.

I removed the idle jet and it is clear and it getting plenty of fuel, but the plug is looking dry. I have only just rebuild the carb for the second time, so both jets were clear on reassembling.

change the spark plug

I have already.  I swapped the Iridium one for a more normal one

I prewarmed the plug with my blow torch.  It coughed once and that was it.

I tried retarding by a couple of degrees.  I got a few coughs out of her and then she gave up again.

Have you definitively checked your ignition timing against tdc on the compression stroke.

Actually I have always worked on the assumption that the timing hasn't changed since it last run, but since we have eliminated the fuel supply and the spark, there isn't much else left.  I've ordered a timing disc and one of those feeler things for checking the position of the piston.  Yeah.. I know, I have used a pencil,in the past, but it is always easier with the right kit. 

I did wonder if it is just possible that there is an issue with the advance / redard? 

You don't need much easy start - a couple of seconds into the carb inlet is usually enough.

Plug out
Turn engine over with your thumb over the plug hole feeling for compression
When compression starts to build
old spoke down the plug hole (marked at thc and whatever distance before tdc)
Put bike in 3rd or 4th gear and rotate rear wheel forwards bringing it to tdc holding spoke vertical.
Now using rear wheel turn rear wheel backwards until the 2nd mark on spoke is correct btdc
Put in neutral
Hold adv/ret fully advanced and move till points just open (I use a multimeter on beep)
Lock it up and kick start

Quote from: rhyatt on 03 May, 2025, 16:00 old spoke down the plug hole (marked at thc and whatever distance before tdc)

Thanks for your help.  Could you please break down this bit? Especially THC, or was that a typo?   

When I finished the rebuild on my DB500 I must have kicked it over 200 times and still no start . firing occasionally but no start . I double checked everything at least 10 times . I kicked it over that many times I strained my leg muscle and had to wait a week to get better . During that week i watched many videos on utube on how to start a bsa gold star . When i went back to it i used that information and it started 2nd kick . Now if it doesn't start first kick it starts on the second , even after 6 months , If everything is correct and it wont go  its down to technic .

Old spoke down the plug hole
When the piston is definitely at tdc the file a line on it at a convenient place on the spoke.

Then

Just below this mark , file another mark at the distance the book says before tdc it should fire.
So, if it is 3/16" before tdc , put your lower mark 3/16" apart.

Ok, now , using a 2nd piece of wire fixed somewhere solid, bend this wire so it makes a pointer against your spoke.
This pointer allows you to move the piston up and down a bit to get the exact firing point

Super, thanks!  I was thinking of going with crank angles. I didn't know that info was available as a linear piston position. 

All the demos I have seen say to kick the engine with the engine just past TDC.  My bike doesn't have a decompressor so it tends to roll past TDC and stop at the point where the points are open and current is reading 0.  Is that OK? Or should I be kicking from just before that point so as to get the spark?   

  BR,  Ian

this is 1 reason that you have the rear wheel and 3rd gear involved, to stop it rolling past tdc - and you can rock the wheel and the engine back and forth to get the right position

the spark HAS to happen JUST BEFORE tdc (by whatever distance the manufacturer says) - only then - with the spark before tdc (btdc) - will the fuel /air mixture start to burn and develop its combustion pressure just after tdc and this burning pressure pushes the piston down the stroke and the bike down the road.

if you have it sparking after tdc the the piston will be half way down the stroke and the energy non-existent.

try the aforementioned routine to check your timing but the piston must be on its way UP the compression stroke and just before it reaches tdc the points must open.

an easy way of watching for when the points open is to watch the ammeter needle(obviously have the ignition on) with the points closed the needle will be on the minus side and the instant the points open the needle come to the 0 centre



with my C15s (no decrompressor) , ignition on  - whatever tickle or choke - ease up to compression and just a whisker over the top - release the kick start lever and bring it back to starting point and then a good swing with your foot down

Just to be pedantic, you said...
Then

Just below this mark , file another mark at the distance the book says before tdc it should fire.
So, if it is 3/16" before tdc , put your lower mark 3/16" apart.

You would need to put the second mark -above- the first mark.   Making the length of wire 3/16 longer.

Also when kicking from TDC, try to extend your swing forwards, for the maximum kick rotation.

That is great thanks!   I am putting the parts of the jigsaw together in my mind. 

 It sounds like we are starting at TDC so that the spark has already occured.  Hence we are starting the kick at the start of the suck stroke and the engine should go through two rotations or all four strokes during the kick and finishing with the spark just at the end of the kick.

  In normal running the spark is just before TDC to allow time for the flame to build, but if the engine is stopped, or turning slowly by hand it will be in the fully retarded state. Might it spark just after TDC?

  Just an observation, but I was watching Hugh Ferrier's wonderful series on YouTube. He, unwittingly bought a Triumph points unit for his BSA C15, and he had to file a bit of the cam to reduce the amount of retard.  I did wonder if this might be the case with my bike. 

  Also I watched a video on how to start a BSA from an 'expert'  and it took him about seven kicks to start his B40(?).  I suspect he might have edited out a few attempts.

  I am off to my cabin to find a spoke, or something similar. 

   Thanks for you continued support.    Ian

capacitor(er?)

Okay.  I found a little fibreglass stick to use in lieu of a spoke.  Right now the timing is at about 2.25 mm  before TDC, but will that be advanced or retarded?  A quick search on Google suggested that it should be around 7.1 mm.  (How the heck do you measure to 0.1 of a mm?!)

I watched Hugh's video again.  The camplate in the points has 12 deg stamped on it.

I needed three hands for this bit, but, pushing the cam-plate around increased the advance from 2mm up to around 15mm. 

With the camplate pushed to the stop, the advance increased to about 15mm.  So, maybe I need to retard by 8mm. 

Quote from: scifi on 04 May, 2025, 08:36 Just to be pedantic, you said...
Then

Just below this mark , file another mark at the distance the book says before tdc it should fire.
So, if it is 3/16" before tdc , put your lower mark 3/16" apart.

You would need to put the second mark -above- the first mark.   Making the length of wire 3/16 longer.

Also when kicking from TDC, try to extend your swing forwards, for the maximum kick rotation.

My apologies, the 2nd mark must be above the 1st mark , to ensure the points opening position is on the way upwards to tdc

Ok 2.25mm btdc
The points should just opening (give or take) here with the advance retard unit held fully advanced.

Put it this way , it should at least start and run here

Pushing the camplate to the right increased the advance from 2mm to around 15mm.  I am thinking that the 15mm is the fully advanced position.  Or did I misunderstand that? 

Just to explain advance and retard in terms of you looking at the points cam.

Determine the direction of rotation of your engine when kicking it over.
Anti clock or clockwise.??

If you wish to advance the timing then the points plate or distributor body need to be rotated in the opposite direction- ie against the direction of rotation.

Conversely , to retard the ignition the points plate of distributor needs to be rotated with the direction of rotation.

I've just taken a pic of my owner manual regarding starting.
I don't have any joy uploading stuff , if you can message me , I'll send to you

If you're still on points ignition, that will be fully retarded. It sounds about right though maybe slightly too advanced. You can only measure 0.1mm (.004") with a dial gauge.

I retarded the timing back to the 7mm position and tried again following the starting technique in the manual. No joy unfortunately.  Just a few pops. Easy start didn't help. 

I'll order a condenser. This is about the only thing I haven't looked at.   

Do you want the timing procedure in the manual

That might be helpful, thanks!

Quote from: rhyatt on 04 May, 2025, 14:00 Ok 2.25mm btdc
The points should just opening (give or take) here with the advance retard unit held fully advanced.

Put it this way , it should at least start and run here

That doesn't sound anywhere near enough for fully advanced. It would be firing after TDC on full retard (ie starting) with this setting.

Quote from: Barnsey on 05 May, 2025, 14:56 I retarded the timing back to the 7mm position and tried again following the starting technique in the manual. No joy unfortunately.  Just a few pops. Easy start didn't help. 

I'll order a condenser. This is about the only thing I haven't looked at. 

I can't remember all the various things you've tried in this thread, but "I'll go and buy a....." is a very expensive way to fault find. The engine will run with the capacitor disconnected (should you believe the capacitor to be the cause) but if I was you I'd start again from basics and check all the various settings and positions.
"I moved it a bit" isn't a good way to get the engine running again as you're then introducing new faults.

What year is your c15 as it makes a difference

Has this bike ever run in your ownership?

It is 'A' plate, 1963.
And, yes, it was running a couple of months ago, although it wasn't easy to start. 

I have checked my work and the original timing was only out by 3 or 4 degrees.

FUEL :  Yes the plug is wet
IGNITION:  Yes the plug is sparking. I checked this afternoon. 
TIMING :  Yes.  See above.
AIR :  Goes without saying really, but no filter fitted to block it.
COMPRESSION : Checked with my thumb in the plug port. Seems fine.
TECHNIQUE :  Various tried.

Any one else got any new ideas before I chuck it of a cliff? 

Just to add insult to injury I discovered that the fuel is stripping the smart new paint off of the fuel tank as well as the chain guard which I spent ages painting.(And I used fuel proof lacquer!) 
 :'(

   

I have sent you instructions for a distributor timing and side points timing

If it was running a few months ago , was it running well or not very well.
Ok difficult to start , but did eventually

You mentioned sparking , what colour spark , must be strong blue crack
Preferably unscrew the plug cap from the lead and jam the ht lead between 2 head fins to give you 1/4" gap for the spark to jump.

Does the spark jump the gap and what colour

Can you borrow a compression gauge to see exactly what the compression is , valve clearances checked correct ?

I read the manual with interest.  It said to set the timing at around 1/16" which is close to 1.5mm, but it didn't say anything about advancing the distributor, so, maybe 7mm fully advanced is correct.   I can check that next time. 

The spark looked pretty reasonable to me, I can't say I noticed the colour, (bluish?).  I can try the gap test next time too. 

I set the valve clearances myself after fitting the new kickstart.  I'll put this on the list, but I have access to a compression tester, so I will try this out before anything else. 

 I run out of time for today so expect to see an update on Saturday,

     Thanks!   Ian

The valves are quite specific in the places where you asjust 1 valve after positioning the other valve carefully.

The earlier book for the distributor engine  I think indicated setting around 1/16" at the retarded.
Whereas , the other books indicated how to hold the advance retard unit fully advanced.

I think you are spending too much time fiddling with the timing, when it might be that the carb is not set correctly.   Do you use any twist grip rotation when kicking..?   Have you got the idle mixture set correctly..?   
My B40 will only start with zero throttle, and needs to run like that for ten seconds before I twist the grip, or else it stops.   I suppose I could make some adjustments to make it better but have not yet tried, as it runs ok when warmed up to temperature.

Well I think that the exercise has shown that the timing is more, or less, correct.  I will measure the compression, as that should be quick and easy, and replace the condenser routinely.  Then I will take a look at adjusting the mixture screw.  I note that the manual says to set the throttle at 1/8th when starting, although this must be a guideline.   After rebuilding the carb I was careful to set the mixture to the same number of turns as it had been before. 

 Is there a procedure for setting the mixture on a non-running bike? 

No. The adjustments need to be done with a warm running engine.
I have found over the years that setting the air screw 1 1/2 turns open from fully closed is a good place to start. Then follow the Amal tuning hints and tips.

I fitted the condenser this morning.  It was fiddly as the new one was slightly longer than the original. It also looks like the alloy edge to the housing, where the points are mounted, is getting eroded. It all looks to be of pretty fragile design and I am surprised that it was at all reliable.  It is tempting to fit electronic ignition, although an old pearl of wisdom is not to modify anything which has never worked until you have it working.  However, out of curiosity, is there an electronic ignition which will work on a 1963 C15 with 6V? 

  As ever I ran out of time (family man), so I'll check the points gap and give it a kick over later this weekend. 

   Ian

Quote from: Barnsey on 10 May, 2025, 11:57 However, out of curiosity, is there an electronic ignition which will work on a 1963 C15 with 6V?   

   Ian

Is this any good to you? Says 6 or 12volt. I run a 12v electronic ignition on my A10.  https://www.classicmotorcyclespares.com/index.php/default/electronic-ignition-self-generating-bsa-c15-b25-b44-b50-with-lighting.html

I checked the compression.  After several kicks I was achieving between 105 and 125 psi, so a smidge on the low side.  A search online suggested it should be 130 to 175.

 Thanks for the info re electronic ignition. I'll check it out.

Hi,

There are Boyer and other EI that just replace the points etc.
A bit cheaper as well.

Dave.

There are also even cheaper devices - Boyer do one - that keep the points but use them just as a very low current switching mechanism. This does away with the condenser / capacitor.

http://www.boyerbransden.com/IDunits.html (http://www.boyerbransden.com/IDunits.html)

Well.... I'll kick it over and see if it starts, now that it has a new condenser, then I'll go from there.  What do people think on the compression. IS 105psi low enough that I should be concerned?

Ian

As in an earlier reply, have you correctly positioned the engine to adjust the valves . It's quite precise.
And I have sent you both books with the procedure inside.
A decent , well adjusted set of points will spark a bike or car fine.
The c15s were lowish compressions anyway.
I use a gammatronic 6v kit on another bike.
And that works fine , from memory about 35 quid.
You're correct , get it running 1st on what you have , in the 60s and 70s I did thousands of miles reliably on points and condensers.

No probs.  Checking the tappets was going to be my next task anyway (and thanks again for the manuals) .  I just wanted a guide as to whether 105psi is bad, as in, we can fix that by tweeking the tappets, or bad as in new head gasket and piston rings.  All this is new territory for me.

ideally , you should have a shade more really. my Son's C15 is quite easy to kick over TDC , but I have never actually measured the psi. i think the C15s were 7:1 CR

conversely, my SS80 is 8.5:1 and is significantly harder to get over TDC

do your tappets carefully , check the spark is a good blue crack (unscrew the HT cap) and lay the end of the ht lead on the head , jam it in the fins to give a good 1/4" gap to jump

My goodness me, what a saga. I imagine you will soon need a replacement knee and kickstart quadrant.
This may be nothing to do with your problem, but I'm not clear that you have quite grasped the ignition timing.
Since they started making motorcycles, BSA have recommended setting the timing on full retard, but since you're only interested what is happening on full advance (where the engine will spend most of it's time),what does it matter where full retard is? Once full advance is set, full retard will take care of itself.
I believe you have tried setting it on full advance, so could I ask how you held the cam in the fully advanced position against the springs? Also, how did you determine points opening? Test light or fag paper?
Sorry if this is a bit basic, but it might be worth remembering that the engine turns clockwise when viewed from the right hand side, and anticlockwise when viewed from the left hand side. You're not making the mistake of thinking the engine turns clockwise while you're on the spark plug side are you?
As has been suggested, get a pencil or spoke and with it in gear, rotate the rear wheel with your hand until you can see the piston rise to the top. Do check and double check that it's on the compression stroke and not on one of the other strokes. put the spoke in the plug 'ole and jiggle the back wheel until you can feel the piston is at the top of it's stroke. (This will not be very accurate, but it'll do for now.)
Holding the spoke on the top of the piston, turn the wheel backwards until the piston has PASSED your timing mark on the spoke (7mm up from the TDC mark.) Then turn the wheel forwards until your timing mark lines up with your fixed point. I use the back of the top of the spark plug hole. It's very important for the piston to always come UP to the timing mark and not down. This takes care on any backlash in the 'distributor' drive train. Now without turning the engine, and the cam held in the fully advanced position, use a test light or fag paper to establish the exact points opening position. Hold the 'distributor' and tighten the screw. Recheck the timing to make sure nothing has moved.
You once said it kicked back badly. This usually indicates the timing is too far advanced.
However, bearing in mind that the motorcycle started before you fitted the new wiring loom, assuming nothing else has changed, then either you have fitted the loom incorrectly, or the loom is faulty (which if it arrived into the UK on a ship, is quite likely.)
A few random thoughts. Quite often bad starting can be caused by a worn carburettor. I have never found a new slide makes much difference as it's the body which wears and distorts through overtightening. If you open the throttle a bit, you may be able to squeeze your little finger into the intake and see how much back and forth play there is in the slide. Don't open the throttle too much, as the most wear takes place at small throttle openings. Maybe you could use a bit of bent wire? There shouldn't be much play at all.
You mention it pops sometimes. Do you mean fires? If it does actually pop, this indicates an ignition problem.
Moving on to your Monobloc, you need to make yourself familiar with the Pilot Bypass and the Pilot Outlet. These are the 2 small holes in the inlet tract either side of the slide. The best  way to physically check these are not blocked is with an aerosol and extension tube. A sonic bath may not clear these.
I believe you have disconnected the feed wire to the points and connected a separate wire directly to the battery, not to the headlamp switch? And still it did not start?
Your compression is a tad low, but it should still start.
You said you purchased a Spark Gap Tester, but you have yet to tell us what gap the spark could jump. Or did you mean you bought a neon tester.....not the same thing.
Perhaps you could let us know the answer to these questions, and we can move on to further suggestions.

Thanks for that lengthy discussion Steve. I will be working through that, I won't give an even longer answer right now. Having refitted the points I will double check the timing. I take onboard your point about winding the engine FORWARDS to the 7mm point to take up the slack in the system.
I will also check the distance that the spark is capable of jumping.

I held the timing cam in the advance position with a screwdriver.

I am checking the points opening and closing with the multimeter.  And I did check the spark with a neon tester, although it is easier to check the spark with the plug out. 

Quote from: Catz on 10 May, 2025, 13:36

Quote from: Barnsey on 10 May, 2025, 11:57 However, out of curiosity, is there an electronic ignition which will work on a 1963 C15 with 6V? 

  Ian

Is this any good to you? Says 6 or 12volt. I run a 12v electronic ignition on my A10.  https://www.classicmotorcyclespares.com/index.php/default/electronic-ignition-self-generating-bsa-c15-b25-b44-b50-with-lighting.html

If you want to go down this route, the kit listed above (out of stock!) is the Electrexworld kit, see here
STK-100D-DC (https://www.electrexworld.co.uk/acatalog/STK-100D.html#SID=826)

Do you have the distributor ignition or the side points.
Reason I ask, the books I sent you were very clear,
Distributor timing was set retarded and sidepoints ignition set fully advanced.
What do you have ?

Well, with only one cylinder it isn't technically a distributor but I would say it is the distributor version, as it has the points in a mushroom at the side of the engine. 

I wasted hours of time this afternoon trying to set it up by both methods,  advanced at 7.1 mm and retarded at 1.6mm (1/16")  In practise setting it up retarded is a lot easier as it is a fiddly to advance the mechanism by hand. 

  However, after several attempts achieving nothing I found an issue in that the new condenser is almost 3mm longer than the original.  This small difference pushed the contact spring out so that it wasn't following the cam through its whole cycle! 

  I can't believe how new parts are so often rubbish straight from the box, and a Lucas part too (red box).

  Can anyone recommend a known good condenser? 

  Running out of time again for today, and it is hot in my cabin!

I think you'll find it's pronounced 'Rucas'.

Modern Lucas shares only the name with the Birmingham original.

If it's a metal mushroom behind the cylinder barrel , then that's refered to as a distributor.
So follow the instructions , from memory 1/16" before tdc in the retarded position , don't touch bobweights.

Have you determined the 1/4" spark gap colour , blue or ?

I put the original condenser back in and tried again with the piston at around 2mm BTDC and retarded .  Once again the dizzy is around 90deg out from where it started.  This is bonkers.  The terminal for the wire is now on the side of the bike which just seems plain wrong.

So I checked the manual and it said to check that the valves are both closed, and it is on the power stroke, which it was. 

Getting weirder.  Surely if the dizzy rotates once in four strokes, then 90deg would be one entire stroke out!  That would put it at BDC. 

I haven't got as far as checking the spark yet. 

The capacitor doesn't need to be inside the distributor/mushroom anyway. Works equally as well attached to the outside of the body.

I didn't manage to get a spark between the lead and a vane, as previously described, but I tried opening a spark plug up to 3mm and it sparked across that gap, so it seems to me that the spark must be reasonably strong. 

What colour was the spark , strong blue crack

If you have a centre punch or small cold-chisel, you can put two marks at the junction of the distributer and crankcase.  This will be a reference point for further experiments.   I did the same with one bike, and found it ran best when the marks were just misaligned by about 1/16 inch.   But at least I knew where to reset it.

I would have said that the spark was pretty thin, and white, although it was hard to tell when it was only there for a split second.  Checking the colour of sparks is obviously a skill I need to learn.

The new timing position is so completely different to where it was that I didn't believe it was right until I had done it several times.  If anyone can tell me how it was possible for it to run at all I will be glad to hear.  I thought seriously about kicking it over, to see what happens, But I could do without any disasters at the end of a Sunday, so I postponed that to next weekend. 

  For the moment I am marking my positions with a permanent marker, as I can clean that off with spirit, but, when I am happy I might use a dot punch as suggested. 

   To be continued......

Ok thin spark.
This could well be the issue all along.
If it is a weak spark outside the engine , even the meagre compression ratio of the C15 could well extinguish this spark when inside the engine .
Basically , blow it out and it won't run.

Was this test using just the ht lead against the engine or a spark plug pushed into the plug cap

3mm in English is less than 1/8" and will be quite useless, although when you get your spark gap tester, I imagine it will jump more than that. If you find it jumps 5/16", then you can forget about the strength of the spark and move on.
By 'vane' I assume you mean 'fin', but it's no good trying to hold the HT lead with your hand. You need to fix the HT lead so there is a gap of 1/4" and then 5/16" between it and the fin or vane, maybe with a bit of wire.
From what you have said, I get the impression you're not setting the timing correctly. Now it is all assembled, just connect your multimeter, turn the engine over in the correct direction of rotation on the compression stroke until the meter reads zero, and measure the piston distance. If it's 1/16" from TDC, your ignition timing is correct, and you can move on to the next thing.   

The spark tester arrived today.  I'll look forward to trying that out at the weekend.  :)

The spark tester arrived during the week, so I have been trying it out, but it is only showing a very weak spark. I am sure it is weaker than with a regular spark plug.  Maybe 1 - 2 mm. Not much more.

 Jury rigging the new condenser didn't help.

   I cleaned the contacts with emery paper. 

  The coil is showing a primary resistance of 2.5 owms and a secondary resistance of or about 6.7kOhms, which is about right.   

While digging around I found a broken Green and White wire from the alternator to the rectifier. That could be it!!!

Hi,

I remember rewiring an A65. Every wire replaced, yes?  Not quite. Not straight away but after several miles a misfire developed that gave similar symptoms as running out of fuel. So, reserve tap on and stop for fuel. All seemed well for a few miles and then the misfire came back.  After popping and banging home I started to think!!!!  I check all the wiring again and all was fine but the only wires I had not replaced were those between the EI stator and the EI control box.  A quick check for continuity and the problem was found.  When twiddling one of the wires there was an intermittent fault.  Problem solved.
So good luck with your broken wire.

Dave.

Can you rig up your battery charger to the battery to give you a good voltage whilst starting.
You have 2 ignition on positions.
1) I for normal battery powered ignition
2) if you turn the key the other direction , through the OFF position , to the E position.
This will allow you to start the bike when the  battery is flat.
Have you put your ohmmeter across the points to check if , when closed , they make a good contact across the cleaned points.
Preferably 0 ohms

Quote from: Barnsey on 17 May, 2025, 11:00 The spark tester arrived during the week, so I have been trying it out, but it is only showing a very weak spark. I am sure it is weaker than with a regular spark plug.  Maybe 1 - 2 mm. Not much more.

 Jury rigging the new condenser didn't help.

   I cleaned the contacts with emery paper. 

  The coil is showing a primary resistance of 2.5 owms and a secondary resistance of or about 6.7kOhms, which is about right.   

You say that you jury rigged the condenser which didn't help.

1) the old, suspected condenser must be disconnected , but you can't do this as it firms part of the assembly

Did you do as suggested and lay JUST the end of the ht lead to the head to give you a 1/4" gap to earth.check the colour of the spark.

Not a plug in the plug cap , the plug cap may be high resistance

You say that you jury rigged the condenser which didn't help.

1) the old, suspected condenser must be disconnected , but you can't do this as it firms part of the assembly.

   I did manage to remove the original  condenser, and I connected the new one by one end only, with a short flying lead to the other end. 

Did you do as suggested and lay JUST the end of the ht lead to the head to give you a 1/4" gap to earth.check the colour of the spark.

Yes I did, but no spark at all, not that I could see anyway. Hence the proper spark tester, although proper is a relative term. It is pretty cheaply made. I am not surprised that I get a better spark with a proper plug, but the spark tester is showing a weak spark.

Not a plug in the plug cap , the plug cap may be high resistance

   I'll check that.  BTW, what resistance should the spark lead be?  I am guessing a few kOhm.

So, with the 1/4" gap from the end of the ht lead to the engine, there was no spark.
The ht lead should be pure copper and therefore nil ohms resistance
What is the connection like where the ht lead pokes into the coil

I've just been cleaning the HT connections between the lead and the coil with emery, both sides.  The HT lead itself is a couple of ohms.   The cap is about 7kOhm 

Further info, the plug cap is LB05F  an NGK  and 5k Ohm.  SHould I fit a non-resister type cap? 

A resistor cap should be OK as long as the plug isn't a resistor type.

It turns out that the iridium plug which came with the bike is resistive, BR8EIX  5kOhm, in a 5kOhm cap. 
The one I bought is an NGK B8ES, so non-resistive,  although it still reads 200 Ohms.

  I have a non resistive cap on order.

5k is a normal ngk plug cap reading, screwed onto a copper core ht lead.
A non resistive b8es should be fine

So, with the copper ht lead to earth and you kicking it over there is barely any spark , or not a decent blue crack irrespective of whether the plug cap is screwed on or not.

What voltage is across the battery with ignition off

I'm getting a 2mm spark on the tester and that is it.  I just put a bit of charge in the battery before testing.

  The battery is a nice new Motobatt MBT6N6, and measuring 6.06V  open circuit. 

The path from the negative battery terminal to the coil reads about 2 Ohms and frame to coil positive is 1 Ohm.  The points read 0.5 Ohm when closed.

Did you manage to realign the 2 contact points after cleaning them.

Yes the points are looking good, well aligned and I set the gap to 15 thou.  The original condenser is back in now. 

  BTW I added extra ground wires from the engine and the headlight to the grounding point on the frame, so return path resistance shouldn't be an issue. 

  Are we at the point of replacing the coil?  Not that I have any direct evidence that there is anything wrong with it.  Is that a more modern improved version available? 

I think you said you'd changed the loom.just to prove the ignition side.
Disconnect the battery side of the ht coil , in other words separate the coil from the bike.
Then run a hot wire from the negative battery straight to the coil.
The cb side of the coil goes via the points to earth.
Now kick it , does it spark a strong blue spark , does it run ?

Remove neg wire to turn it off

Assuming you really do have a 2mm spark, as I said before, this is no good at all. It should jump 5/16" which could be about 8mm, but I don't know. They didn't use foreign measurements when I was at school.
As Rhyatt has suggested, make a direct feed to the coil from the battery, but this was suggested many moons ago. I hope you have done it by now!
If you like, you could remove the coil, connect a battery to it and test the spark on the bench, by repeatedly touching the live wire on the coil terminal. It should spark every time you remove the feed wire.
If you're not sure about your spark plug tester, I have heard that you can get 2 old spark plugs, break off the earth terminals, fit them opposite each other at 90 degrees to the vice jaws with cable ties and with all the electrical connections connected, wind the vice in and out to establish the exact gap. But this might be overkill.
A 1/4" gap will indicate the coil is producing 10,000 volts and 5/16" will indicate 15,000 volts, which should be enough to start your machine.
If it were me, I would simply purchase a new coil, and send it back if it makes no difference. Then you will know if the coil is OK or not, irrespective of any resistance readings.
Have you tried hitting the coil with a hammer? I quite often find this works wonders with lots of things.

I'll try adding a direct wire from the battery to the coil today, but I am not expecting too much from that.  The path through the switch and ammeter really is only a couple of ohms.  Also this is all stuff I have done before.  I wonder if I should have started a new thread in the forum as I went through all of these tests to get it working the first time and then, after a couple of months laid up it gave up again. 

  I have a new, non-resistor type cap on order and I am hopeful that will help.

  The idea of setting up two plugs on a vice is a good one. I have seen this done on television. although I don't have a pile of old plugs sitting around to use, so , probably just as well to order a new coil if it comes to it.  Can anyone recommend a 6V coil other than Lucas?  I am going off of Lucas as the quality is what might be called 'variable'. 

  Expect an update later today. 

Adding a wire directly from battery negative to the coil didn't achieve much in terms of spark strength. It was much the same. 

  I double checked the timing, and, yes, it was set up to spark at the end of the exhaust stroke.  This completely baffles me as it was running and I hadn't altered the timing. 

  Anyhow I set up the timing on the compression stroke with both valves closed.  And then I switched on and gave it a kick. 

    It initially looked positive as it kicked back on me just as I was starting my kick.  It didn't hurt thankfully.   But I thought I was onto something.  However I kicked it a few more times and not so much as a chuff.  It looks like I will be waiting for that spark cap to arrive. 
 

If you've bypassed everything and still have a weak spark
You've cleaned and aligned the points and exchanged the conder with no improvement in spark strength.
Then a new ht coil is the only thing left frankly.
Lucas /wassell 6v coils are about 20 quid  give or take.
I use Chas bikes and Kidderminster motor cycles as reliable parts people

Sorry I was asking you to repeat work. I wasn't clear you had previously fed the coil direct.
Anyhow, good, you now know that the feed from the switch is OK.
You could get a Bosch coil from Tanya.
As I said before, kicking back is usually caused by over advanced ignition timing.
Form what you have said, your ignition timing is moving all over the place, so it is worth checking it repeatedly in the way I described, after you have kicked the engine over a few times. It shouldn't take long.
If it does keep altering, then I would remove the "distributor" and examine the gears and drive train (or whatever the C15 has.) Maybe the drive is slipping somehow?
However, with a 2mm spark I doubt if it will ever start.
Always remember to only do one thing at a time. If you do 5 things and it starts, you will not know which of the 5 things was the problem.
Chin up, keep at it. You'll soon have it started and be able to give it a damned good thrashing.

I don't think the ignition timing is moving by very much.  It is just a question of setting it up on the right stroke.  I am still bothered that the engine ran with the points breaker 180 deg out.  I have a photo of the bike early on in the job and I can clearly see the distributor in that position. 

  Anyhow, the new Lucas coil and non resistor cap are on order.  Next weekend I will be on holiday, but only for a couple of days, so expect a bit of a gap before you hear from me again.  I can just tell that I will be on hols with my family and itching to get on with the bike.  That is what usually happens.  :)



   

If it ran with the "distributor" 180 degrees out it suggests you're now trying to time it on the wrong stroke. Very easily done.

That's what I thought, but the instructions in the manual said to set it with both valves closed, which they would be at the start of the power stroke.  I removed the valve covers and both rockers rattled loose. If it was the start of the induction stroke, the inlet valve would be open (i.e. not rattly). SO  I am sure it is correct.....  That is unless anyone can suggest otherwise?   ???

if you were on the stroke with the valves closed , then you needed to continue upwards with your spoke or whatever down the plug hole and the engine in 4th gear and on the stand gently nudging it upwards to TDC then back a whisker and the points should have JUST begun to open.
the handbook says .007" which is just about the same as the inlet valve clearance gap ie barely anything BTDC

The Lucas coil arrived today but it is a different size to the old one!  DOH! 

48mm vs 40mm in diameter.  I'll give it a try, while I have it, and then I might be looking for a clamp bracket for it.   Can anyone recommend a clamp which will fit both bike and coil without costing a pile of cash? They seem to sell for crazy money considering what they are. 

Getting back to the cam and valve opening discussion.   On the non power stroke at TDC, the valves will have an overlap, where they are both open a small amount. 

Racing cams have a large overlap of maybe 50 degrees each.  Road bikes have much less overlap, and lawnmower and industrial stationary engines have zero overlap.

The position where both valves are open the same amount is -nearly- always at TDC. and is a good way to check your cam timing.

Kidderminster motor cycle
01562 66679
Remember to give them your new diameter

Unfortunately, your new battery is flat.
A 6V battery reading 6V is considered to be 100% discharged.
When it reads 6.4V it is 100% charged.
However, I'm sure this is not a problem. You simply need to charge it up. Make sure it holds 6.4V for a week or two.
I wonder if you could make up a packing piece for the coil bracket from a bit of scrap alloy, or maybe some strips of old inner tube?
This needn't concern you for the time being, but an AGM battery is not necessarily ideal for an alternator with switched coils and no zener diode. They prefer electronic regulation. But if your luck is anything like mine, the alternator won't work anyway.
Let's just get the thing running first.
 

Okay.I am sure that the AGM was not fully flat, but I have put it and also the old twin cyclons on charge.
I will see if they are still holding charge when I come home from holiday next Thursday. 

The new, non-resistor cap has arrived so I can try that out too. 

The new, bigger coil turns out to need a thicker lead too, around 11.5mm vs 8mm, so I opted to order the correct coil. I might return this one, we will see.   

I wouldnt leave batteries on charge for a week
overnight is fine , but not sitting there on their own all week on charge

Yes if an old fashioned charger, but a modern intelligent model would be OK.

In theory, but not in practice. I personally know of several batteries that failed too quickly by being left connected to maintenance chargers, Optimates and Lidl's finest battery chargers.
When Tayna were contacted re the failures they advised against long-term connection.

I think this talk of wire sizes is becoming unnecessarily complicated. You just need to connect a feed wire to the coil.
However, to complicate matters even further, if you mean what is commonly known as 11.5mm squared, this would be starter cable capable of taking about 70 Amps. If you mean 11.5mm diameter, much the same would apply.
The largest cable I would use would be termed 28/030, 2mm squared, and will take up to
17.5 Amps. This is about 3mm diameter. Otherwise, just use what I would call normal cable (14/030, 1mm squared) which will take up to about 9 Amps.
Your coil should draw no more than 4 Amps, hopefully less.
Was it a Mr. Faraday who told you to use 11.5mm cable?
I don't remember coil feed cable being particularly large.
For the time being, just connect a bit of wire and try to start it. Bear in mind, if it kicks back, it's probably over advanced (just turn the "distributor forwards a bit). It would not be good to break your ankle just before your holiday.
Hope you have a good one.
   

Quote from: V500 on 23 May, 2025, 09:58 In theory, but not in practice. I personally know of several batteries that failed too quickly by being left connected to maintenance chargers, Optimates and Lidl's finest battery chargers.
When Tayna were contacted re the failures they advised against long-term connection.

The original question was up to a week which I think would be fine. I don't leave my batteries on permanent charge but refresh any on bikes I'm not using with a couple of days with a CTEK charger.

Also, re wire sizes: I use 1mm sq thinwall cable which is rated at 16.5 amps for everything on older bikes. The most you would see anywhere is about 10 amps from the alternator if it's running at full whack.

These cables are available from VWP as well as my preferred supplier (as they're round the corner from me) ALM. https://www.almsolutions.co.uk/index.php?main_page=product_info&cPath=3_60&products_id=42

ALM also have bullet connectors etc.

I do too. Easy to use when inserting through sleeving etc and more than adequate in it's rating.

Non resistor spark cap fitted.  The spark still looks pretty weak to me, and inconsistent. Not sparking on every kick.   I now have the right coil to try in, but it came without the HT spike to go on the end of the lead.  Now on order from the nice chap at Kidderminster motorcycles. 

Short term fix.
Use a scalpel to trim off 1" of ht sheathing and spread the copper wire out into a ball when you poke the lead into the coil

Quote from: rhyatt on 30 May, 2025, 13:17 Short term fix.
Use a scalpel to trim off 1" of ht sheathing and spread the copper wire out into a ball when you poke the lead into the coil

Always did it that way!☺️

when I do have the brass clip thing, I always solder the copper to it

Sometimes that seems to make the acorn too "tall" to get more than a thread or two into the coil terminal, I find.

Right, I've fitted a new coil, spark lead and non-resistor plug cap.  The spark is looking more reliable, although I haven't persuaded it to jump more than 4mm.  I used a shiny new HT spike on the lead and I soldered it on just for good measure.   

Not much left in the way of it bursting into life and you hurtling towards the sunset!!!!!

I've given up for today. I need some rest time before work tomorrow. But I'll tweek the timing next weekend and give it another kick. See what happens.

 I set the points timing on the crown of the cam, which isn't quite right. It should be on the rise.  So that needs adjustment first. 

If you do it on the crown it's wrong.
I thought you'd sorted the timing with your meter on beep telling you when the points just opened.

Obviously you've already got the piston in the right place on the right stroke

Yes, my mistake, but it doesn't need adjusting by very much. 

However, I have a query about the ignition coil.  I wired positive to breaker and negative to switch, being as the bike is positive earth. OR, is this misleading and makes the assumption of a negative earth machine? 
Should I connect the negative terminal to the breaker?  Although this is contra-intuitive, the two coils are commoned to the negative terminal, so it seems to make sense that this side should go to ground via the breaker. 

 Earlier coils were labelled as contact breaker and switch. 

All the sites I look at seem to say to connect negative to negative and positive to positive, but I am not convinced that this is right. 

If your bike is pos earth , then the coil terminal +( or the cb) should go to the points.
And the negative of the coil( old sw) back to the ignition switch.
If you've converted your bike to neg earth then reverse these of course.

That is correct in theory but in practice I don't think it makes much difference.

Both ryatt and iansoady are, of course absolutely correct. However, although this will be of no use to you, one way of telling if the coil connections are reversed, is to use an oscilloscope where the trace spike on points opening will be upside down.
Moving on, a spark jumping only 4mm is no good at all. I would remove the coil, and connect it to a good fully charged battery showing 6.4V i.e Positive to positive and negative to negative, with the HT lead fitted, and as you remove the feed wire there should be a big fat spark of about 8mm. But don't leave it connected for any length of time.
Can you confirm that your battery was showing 6.4V on your return from holiday?
If both your old and new coils were only jumping 3 or 4mm, it indicates there is nothing wrong with your old coil.
Since you are now feeding the coil direct from your fully charged battery, assuming the earths are good, then the only reason I can think of for a weak spark, is a problem with the points or condenser.
The points gap should be 0.015" at their widest opening. If you are not sure, you could establish this using feeler gauges.
It's possible, when using a meter for ignition timing, to go a little beyond points opening. I use a fag paper, where the slightest slackening of grip indicates points opening. These are available at your local Tobacconist.

P.S You will have to earth the piece of metal you are sparking to.

I've set up a simple improvised loom on the bench with the original coil and a variable power supply.  I achieved a 10mm spark. 

The mottobat battery has been holding 6.4V. With the Mottobat battery I achieved around 8mm.   I didn't try the Cyclones.  They are not holing voltage.

Quote from: Barnsey on 07 Jun, 2025, 15:25 The mottobat battery has been holding 6.4V. With the Mottobat battery I achieved around 8mm.  I didn't try the Cyclones.  They are not holing voltage.

Just a thought. I'm wondering if you may have a high resistance somewhere in the ignition circuit. With the battery disconnected and the contact breaker points fully open try measuring the resistance between the wire that connects to the -ve side of the battery and the supply side of the coil (I'm assuming your bike is +ve earth). You should see a resistance of less than 1Ω. Sometimes the resistance build up across the ignition switch and multiple bullet connectors can drop the voltage to the coil considerably.
It's also worth measuring the voltage across the battery and then between the battery positive terminal and the -ve connection to the coil when the contact points are fully open. The coil won't be drawing any current with the points open and the voltage at the coil should be much the same as measured across the battery, certainly no more than about a 0.25V drop.

Excellent. Now we're getting somewhere. So your new coil and battery are working well. You could test the old coil. It's probably OK.
I completely agree with Derek, although I hope you're bypassing the ignition switch and feeding directly from the battery? With this direct feed, I hope you're NOT switching the ignition on out of habit? Bear in mind that the bike started well before you rewired it. Don't forget to disconnect the feed before you pop indoors to bathe your swollen knee in Epsom Salts. I would also check the resistance between the points base plate and the 'distributor' body and the body to the crankcase. While you're at it, check the resistance between the battery positive and frame.
Are you sure the points are assembled correctly with 0.015" gap? Is there much sideways play in the 'distributor' camshaft bushes?
Are the advance/retard springs fitted and in good condition? I ask this because it could be that when you kick the engine over, the ignition goes to full advance, which may be why it kicks back?
Keep at it.

Hi Barnsey and contributors to this thread, can I congratulate you all for your tenacity. I have ridden motorcycles for many years however stayed away from the mechanics and starting to learn, this thread has been so helpful to me with wrestle to understand the complexities creating efficient spark/fuel combustion... Keep at it Barnsey... I'm looking forward to reading the words.... 'It's working'

Okay, I have been measuring resistances.  1.5 ohm battery negative to coil.  0.5 ohm coil to points and another 0.5 ohm points back to battery positive. 

  Closing the points and measuring battery positive to battery negative gave 2.8 ohms including the 0.8 ohms of the coil itself.  So I have 2.0 ohms to lose.

 Both paths go through the ignition switch, so maybe I will need a new switch, but I will try some more experiments first.   

You will never be able measure low ohms readings of less than 1Ω accurately as the meter leads have some resistance themselves but you can get a better idea by touching both meter leads together and seeing what ohms reading you get. Subtracting this value from the readings you are getting will give you a more accurate result.
Assuming the coil has a resistance of around 3Ω and there is a 1.5Ω resistance between the battery -ve and coil and that the battery voltage is 6.4V. Then total resistance, ignoring the 0.5Ω to earth, is 4.5Ω which will draw a current of 1.5A. This will mean a voltage drop of 2.13V at the coil. So your 6.4V at the battery is going to drop to only 4.27V at the coil at best. No wonder the spark is weak.
With the wires disconnected measure across the ignition switch terminals. When the switch is at the ON position you should see almost zero ohms. If there is anything more than about 0.5Ω the switch would be replaced.

OK, taking onboard the resistance in the meter,  the battery is showing 6.4V but I am seeing 5.4V at the coil, so I am losing a volt in the wiring.  I replaced the lighting switch during the project, but not the ignition switch. Hence I have taken a leap of faith and ordered a new ignition switch at around £50 (ouch!)  and we will see what effect that has. 

A 1V drop is still a fair bit (20%), You should make serious look to see where the resistances are that are dropping the voltage; the switch and every connection from the battery to the coil as well as the earths.

Yeah!  My gut feeling is that this is a host of small issues, rather than one big issue, and I will eventually knock them all down, but it does make me feel like I am chasing shadows. You know what I mean? The compression is just slightly low. Resistance here is just slightly high. Voltage there is just slightly low, maybe the fuel is just slightly lean, etc.   

Always try the easy (obvious) things first. Change the spark plug, they can fail to spark under compression. Members here have covered all the bases, wiring connections, H/T leads etc. Worth checking the points gap, for the sake of 5 mins.

If you start with 6.4 v with ignition off and then turn the ignition on , if the points happen to be open , then there'll be no change in battery voltage.

 the volts will certainly drop if the points happen to be closed (that's why the ammeter kicks over), as the coil will consume around 3 or 4 amps.

Normally, the voltage is still fine to start the bike and then the engine recharges the battery.

I've sent you meter readings in the past to check the quality of the points , from the +ve side of the coil wire down to earth via the points closed. Should really be 0 ohms proving the points are good.

But you say old and new coils give a good crack spark with your motobatt battery , you're fine there then.
Hopefully, this healthy spark is in the right place timing wise and I've gone through with you how to check that.

I sent you valve adjustment instructions , did you check the clearances and adjusted.

Yes , from memory , your comp ratio was a bit low , but ok to start (and could well improve with running
There's not much left

It's starting (no pun intended) to look like there is a problem with your wiring loom or connections.
So bypass the loom, and remove all the coil wires. Connect a new wire from the coil to the points, and connect a wire from the coil to the battery negative and start your engine. It shouldn't take too long.

I have a few cables with crocodile clips on both ends to check this sort of thing. It just takes a moment to bypass suspect components.

I seem to recall the by-passing of the wiring has been suggested before in this thread, but even still, the loss of 1V seems to be a red herring.
They were never that finicky when plodding to work in all weathers on minimal maintenance.

It is possible to see a good voltage somewhere but as soon as a load is applied it disappears. Often happens if LEDs etc are in the circuit.

Quote from: iansoady on 09 Jun, 2025, 10:20 ...Often happens if LEDs etc are in the circuit.

Please explain?

You can get a back feed of low current through them. I once spent ages trying to isolate a fault in a caravan - a wire had come off a switch but an LED indicator was letting voltage through so it looked as though it was getting where it was needed.

I missed the result of temporary removing all wires from coil etc.
Just a wire from pos on battery to pos on coil.
-ve battery to ground
-ve coil to distributor.
With clean points, new coil and plug, tickled carb, half choke you will get something.
Have you done EXACTLY as above?

Just to clarify , if you're original pos +ve earth , then the + of the coil must go to the points and the battery neg -ve on the battery to the ignition switch or straight to the neg of coil
This'll give you a spark nicely when you kick it and the points open and close

Quote from: iansoady on 09 Jun, 2025, 11:18 You can get a back feed of low current through them. I once spent ages trying to isolate a fault in a caravan - a wire had come off a switch but an LED indicator was letting voltage through so it looked as though it was getting where it was needed.

I see what you are getting at. The cathode leg of the LED will show the supply voltage when there is no current flowing through it. Although I'd expect that the LED would light up when a load is applied. Any circuit with a high resistance in it can show a full voltage until a load is applied.

Quote from: rhyatt on 09 Jun, 2025, 15:40 Just to clarify , if you're original pos +ve earth , then the + of the coil must go to the points and the battery neg -ve on the battery to the ignition switch or straight to the neg of coil
This'll give you a spark nicely when you kick it and the points open and close

Thanks for confirming has +ve earth.
I lost track of which earth he had, but the principle remains the same of trying a simple total loss battery-coil- points system excluding the rest of his system.

Not a happy Bunny today!

I fitted the new ignition switch but the resistances, which were already negligible, haven't changed much. 

Unfortunately I tried to kick it over with the bike in gear.  I guess that I am fuzzy minded with all the stuff in my head.  I realised that it felt different but didn't put two and two together.  Anyway there was a snap and my foot went down with a jolt, leaving me feeling like I had broken my knee.  It looks like the pawl in the ratchet has failed and I need to open up the engine again! 

  Does anyone want to buy a bike? 

oh dear
is it possible to try and bump start it - just to see if it will fire

It's definitely a thought but I will need a hand to get it down the steps of my cabin.  Let me think on it. 

  It took a bit of effort to replace the kickstart last time, but I am hoping that it will take half the time on the second ocassion. Let's try and be positive.   :-\   

Hi,

If the pawl has been replaced and not had much use since it may be OK. Once you realised it was in gear did you try it again to see if was not engaging?
As it was in gear the wheel may have caused the gear box to rotate quicker than you were kicking it, hence the lack of engagement of the pawl.

Dave.

Yes, sure I did, several times. 

I opened the engine up and removed the kickstart pawl, which was indeed very worn with the edge deformed to a burr. 

 Astonishing being as I fitted it new, and the bike has only run a couple of times. 

 So, is this a result of it being a lousy design?  Or maybe a poor quality pattern part? What do people think?  Can anyone recommend a decent part so I don't end up doing this again? 

  Thanks, 

     Ian

Most likely poor quality pattern. Where did youu buy it? I generally find draganfly better than some of the others.....

It was ages ago, so I don't remember, although probably via EBay.   OK, I've ordered from Draganfly this time.  I will see what arrives.  Please pray that I have ordered the right one. 

Another question which I might have asked before, is there a gasket available to be between the inner side cover and the block?  I don't think it was ever made with one and I used Hylomar last time. 

I found a gasket on EBay, so I ordered that this time.  I also took the opportunity to check that the 0 degree mark on the crank gear lines up with the dot on the timing gear, which it does! 

Hi,

See the thread re gasket or not. Using a gasket will increase the end float of the main shaft by the thickness of the fitted gasket.

Dave. 

I presume there are other private messages circulating re this (otherwise where did info about being in gear and starting come from?)
Ignition switch wiring referenced again but still no total loss start just to prove the engine runs and this ignition coil/distributor/carb are ok.
If you get the bike running you can then work backwards to find the wiring fault.

Thanks Neil, Right now I  have the bike in bits pending the new kick start parts, so it might be a couple of weeks before I get back to looking at the electrics. 

  I am wondering if there might be too much end float in the gearbox shaft preventing the pawl of the kickstarter from engaging properly. Certainly only half of the width of the pawl was mashed. Something for me to look at when the new pawl arrives. 

 Also, the steel stop for the kick start was out of position, but I can't be sure how long it was like that, or if it just moved during disassembly. 

  If anyone has any other bright ideas of things to check before I reassemble it,  I would be glad to hear.

Hi,

For unknown reason BSA made the pawl like that.  It only engages on about half of its width.

Dave.

Quote from: iansoady on 14 Jun, 2025, 14:08 Most likely poor quality pattern. Where did youu buy it? I generally find draganfly better than some of the others.....

Yes, all you then have to worry about is the Drags, "this item is on back-order..etc" usual response.

Yes the pawl is on order from Draganfly.  I'll just pray that they can send one out during the week. 

And yes, the most annoying and frustrating part of this hobby is the poor quality of parts available. They are either worn out originals or badly made copies.  And I can't believe some of the mistakes which they make in the manufacture. 

  I might investigate turning the points assembly around , while the engine is open, so that the connection is at the back.

  I might investigate turning the points assembly around , while the engine is open, so that the connection is at the back.
[/quote]

May I ask why you wish to turn the distributor around , my Son's distributor screw connection points outwards , I sent you pics of a satisfactory distributor.

Hi,

I recently bought a pawl from C&D Autos.  They do not have website but if you ring earl enough they get things in the post the same day.
Call 01564 795000 or email canddautos@gmx.co.uk

Dave.

There are still new old stock parts out there, including the kickstart pawl

https://www.ebay.co.uk/itm/196423262542

DOH!   I've ordered the pawl from Draganfly now.  The new-old stock would have been better. 

Having tweeked the timing ,to get it right, the connection to the distributor was pointing in completely in the wrong direction and I had to extend the wire to reach the connection. Not that this is important right now. 

The kick start pawl is here but I have spotted a crack in the inner side cover where the spring attaches.  Annoying as this is already a replacement for the original which was itself cracked. Anyway I am shopping for a replacement on Ebay.

Quote from: Barnsey on 16 Jun, 2025, 17:00 DOH!  I've ordered the pawl from Draganfly now.  The new-old stock would have been better. 

Having tweeked the timing ,to get it right, the connection to the distributor was pointing in completely in the wrong direction and I had to extend the wire to reach the connection. Not that this is important right now. 

Sounds like you may have timed it (distributor) 180 degrees out?

i think by now i'd be considering cutting my losses and dob it in for a bus pass

Counsel of despair! If you have compression - you don't actually need that much, somewhere close to correct mixture, and a spark at approximately the right time it should at least try. If you're sure about the ignition timing I'd try a squirt of asy start in the carb inlet. If it fires then the problem is fuel. If no sign of firing then ignition.

I may have suggested this before.......

Quote from: iansoady on 22 Jun, 2025, 14:22 Counsel of despair! If you have compression - you don't actually need that much, somewhere close to correct mixture, and a spark at approximately the right time it should at least try. If you're sure about the ignition timing I'd try a squirt of asy start in the carb inlet. If it fires then the problem is fuel. If no sign of firing then ignition.

I may have suggested this before.......

I usually use brake cleaner . it will fire anything that sparks at the right time .

I found a nice side cover on EBay for around £20 with p&p so that is on its way to me now. 

Yes, I am definitely on the right stroke. Both valves are closed.

Yes, I have tried Easy start, but no joy. We had already concluded that it was electrical before the kickstart broke for the second time.   

I was just at the point of testing it out with the new ignition switch when I broke the kick start. 

 It has had a new loom, coil and I tried jury rigging a new condenser.

  I can get a spark of around 10mm on the bench but not on the bike.

 I haven't tried new points, but the existing ones look to be in good condition.

  Le me reassemble the engine with the new side panel and then we will go from there.

  And, maybe not a bus pass....  but sticking with my Toyota Aygo seems a serious good idea right now. 

If you've aged a 10mm spark (just under 1/2" then the coil is fine on a rig .
Now duplicate that rig on the bike - battery neg to coil neg , battery positive to engine(do it to engine 1st , frame later) and coil neg to points.
Plug out , kick it over should give you your fat spark as on the bench rig.
If it sparks , then move the battery pos to the frame earth , still spark ? Good leave it there and proceed to start the bike.

Worry about the battery neg going via loom and switches later

The new cover arrived today, and bead blasted too.  As a bonus it already has the bronze bushes fitted.
I'm hoping to fit it this weekend, but we have hedges which need cutting, so it might get pushed back.

Nah, you don't want to push it back, you really need to cut it for a proper job... ;)

Rhyatt is absolutely correct, but you don't seem keen to take his advice, offered more than once.
I think I might also run a separate earth cable from the distributor to battery earth, just to make sure. If you have a spark, I would also recommend confirming that it will jump 10mm as on the bench.
If it's still a weak spark, then disconnect the wire at the points, and just jab the wire to earth. This should give you your 10mm spark each time you jab. If you get a good spark, this will indicate that the points are the problem, perhaps assembled incorrectly?
Please make sure you disconnect all the loom wires from the battery, coil and points. If the loom is faulty (and it ran before you replaced the loom), leaving it connected could affect the results. Check the battery is still reading 6.4 Volts.
Regarding kickstart wear, bear in mind you have probably given it 10 years of wear over the last few weeks.
I'm surprised your knee is still working, but that is why you have 2 knees.

It looks like I had the kickstart stop plate in upside down:

 (https://www.classicbikeshop.co.uk/triumph-350-500cc-unit-twins-kickstart-stop-plate-1957-74-oem-57-1157.html)

Maybe that contributed to the fracture in the side plate. It looks like the tapered end goes downward? 

 I'm now reassembling.

  I am always grateful for all advice, but sometimes things get in the way and I don't get to try it out in as short a time frame as I would like.  In this case kicking the bike over when in gear, and then the kickstart breaking again. 

  I'll try the stripped down minimalist loom just as soon as the bike is back to being in a kickable state. 

And... ohh yes,  I added extra grounding wires to the engine and headlight ages ago.

  This has been going on so long that it is getting hard to remember  what I have done in what order.  If ever I do another project like this I will keep a paper log book!      (Serious amount of IF in that!)

New problem.

 The new side cover has locating dowls in difference places to the old one so I need to move them around in order to get it to fit on the bike.  It looks like they were originally a push fit but they are not budging now.  What is the best method to remove them without destroying them in the process?  Is it the old,'heat it up in my wife's oven till they fall out' approach? 

Forget I said that. Even with heat an penetrating oil, the metal of the dowl was so thin that it just tore.

 I'll carefully file it flat and then drill it out.  New dowls appear to be still available. 

Drilling out the dowl went without hitch  (Phew!).  New dowls on order from Feked.  I had a hunt around my workshop to see if I had anything the right diameter to re-purpose, but no joy.  Apparently some brake pipes are 7.8mm 5/16" . 

  Anyhow, it looks like I will be reassembling the gearbox next weekend.  Then back to electrics. 

Pay attention 007.

I suggested running a separate earth wire from the distributor to battery earth, in the unlikely event that the distributor is not earthing to the crankcase, for some nefarious reason. It shouldn't take too long.