Hi Guys, I finished the rebuild of my '71 Lightning and I'm pretty pleased overall. However I'm now into the snagging stage and there are a few issues.
The first is the terrible starting. When I can get it started it runs really nicely. it ticks over when it's warmed up a bit, it revs easily with no faltering etc, no smoke. I took it out for it's first ride yesterday and it was a joy (apart from the worry that it would stall and I wouldn't be able to restart it!) pulled like a train and behaved really well.
Normally though it takes a minimum of 6 kicks to start it more often ten or 12 and quite regularly 30+ and then I give up! when I first attempted it I used the same technique as on my Triumph which is open to full bore as you kick, usually works first time. I read somewhere here that almost no throttle is required for an A65 so I tried that and it seemed to help a little but today nothing is working. I've tried half choke, no choke, full choke. I've had the carbs off and cleaned them many times. The spark looks ok the fuel is fresh, I've checked the float heights, I've put a bright bulb on the power to the Boyer and that's fine. I've put the coils and the HT leads on my Triumph, started first kick.
Some context: The Carbs are brand new Premier concentrics with the standard jets, needle and slide. The needle is at the top notch as per manual but I tried the middle and no difference. Boyer system installed as mentioned. air screws 1 1/2 turns out. I managed to start it and strobe the timing, now spot on.
Running out of ideas now :-\
Thanks in advance
Glenn
As its a new engine build it will prefer to run slightly rich until you have got a few hundred miles on it. Try setting the idle screw about 3/4 a turn out from fully screwed in. as the motor beds in it will want setting again.
At either stage, when the engine is hot, I find a minimum of 10 miles is ideal, set the idle mixture screws until the engine ticks over its fastest then turn it back in about the width of the screwdriver slot.
Then when you start the motor from cold, your choke should operate as normal - always try the first couple of kicks with no choke, then if it doesn't start. Tickle it again and lower the choke.
Note also that half choke isn't a thing on amal carbs, as soon as the choke is within the slide it can be fully open and the engine would not know. Half choke is only a thing on carbs with butterfly choke carbs - like some keihins.
I notice you make no reference to flooding the carb with the tickler? If you don't that could be the reason. All my BSA's have needed to be tickled until petrol starts to come out of the button.
Give it a try and let us know how you get on.
Allan, many thanks, really useful insight. I definitely hadn't realised half choke was not a thing. I don't understand that yet as the choke slides go up or down relative to the position of the lever but I guess if I'm not going to open the throttle much then the slide will be hidden in the main slider? So I guess I give it full choke or nothing. My Triumph doesn't even have a choke any more but it had a lever on the top of the carb which was either up or down, nothing in between which kinda confirms what you say.
Ed thanks, Sorry I forgot to mention but yes have been tickling both carbs till petrol comes out.
Update: I have been going through all the checks for the 375th time and this time I cannot get a spark. I seem to have no continuity through either plug cap. Quite how they have failed since i turned the motor off yesterday I really cannot explain. I thought I must be doing something wrong so I checked one from the triumph and the resistance was as it should be.
Is it normal to run with suppressed caps on these bikes? I swapped the cap from the Triumph the Beezer and still can't get a spark but at least I feel I have a direction of travel now!
Thanks for your ideas, I'll update when I have some news
Cheers Glenn
Hi Glenn. Yep you have that right. Soon as you start lifting the choke, it is quickly hidden by the slide (if the throttle is closed) so for starting it's all or nothing.
Suppressed caps should only be used with electronic ignition. However suppressed plugs (instead of caps) are deemed to be more reliable and the 5kΩ suppression is more accurate, ie you could measure a cap and it be more or less than the 5kΩ.
Try checking where the leads go into the coil. If they are the little brass fittings, they are not very good, and with some coils, work themselves out easily.
Coil terminals are readily available from Accuspark on eBay, they even sell a cheap little plastic crimping tool, which works really well despite looking like it might break on first use.
Also check you are getting 12v to the white wire going to the ignition box and the red terminal on the battery (or the white wire going to the coil if your using points still).
Many thanks Allan, great stuff again.
I think this is the problem. The caps I had were 10K ohms though I cannot get a reading through them now The ones I tried from the Triumph I thought were 5K but on closer inspection they seem to be 15K which might explain why I'm still getting no spark.
So new caps on order and lets see if that sorts the problem. Boyer it seems recommend 5K or no resistance for a mark 4. Wish I'd read that before more or less putting my hip out kicking the @*^! over. Continuity on the leads seems fine. Fingers crossed.
Interesting that the 15K ones work fine on the Triumph with Vape electronic Ign.
Yes 12.7V at the white wire. Also stress tested it with a bright bulb to check the connection doesn't break down under load.
As a note, the 10 K caps had Champion branding on but I think they are copies which seem to have failed after 4 miles! I would avoid those. I could not get 5k original ngk or champion that were not red so have gone for some NGK copies by K&S. Working on the principle they at least have put their name on them. I'm hoping they'll be OK. If not I'll try unsuppressed NGK's.
Many thanks for your help
Cheers Glenn
The unsuppressed NGK ones work well. They are often available under the farming and agriculture sections. You may also find them cheaper in such environments as opposed to looking up the bike sections on eBay.
Decent caps with N3 or N4 plugs and you shouldn't really have any issues. The only tripping point I found once was one of the wires from the trigger plate to the black box went high resistance. Some oxidation on a contact. The bike left me stranded and I was lucky to get a lift. When I metered out the wires they read high with the trigger coils still connected. Then I checked the individual leads and found the issue. Disconnected and reconnected and it sorted the problem.
Hi guys, well the plot thickens.
New caps arrived, still no spark. So I rechecked the coils, The right shows 2.2 Ohms between the low tension terminals and 9k Ohms between the high tension and low, neg and pos. About what I would expect.
The Left however shows no continuity between the low tension or between the positive and high tension. It does show 8K Ohms between High tension and negative terminal though. I assume the Left coil is %$@^ed.
I then thought I'd test the boyer box. I connected up the plus and the minus from the box to the coil I believed to be working (6v Lucas). No spark when I touched the wires to the stator plate together.
Does this mean the Black box is fried too? If so, that's not a bad effort for the 4 miles the bike has done!
Any comments gratefully received.
Thanks Glenn
If you have boyer, then the box is "told" to switch the coil by the rotating magnet whizzing past the little coil on the stator plate.
This little coil generates a tiny AC voltage when the magnet whizzes by and it is this ac pulse that tells the box to switch the coil on and off.
So, test 1 , disconnect the wires from the little stator coils and put your multimeter on AC then kick it over watching the meter readings, hopefully you'll get a tiny voltage , repeated each time the magnet goes by the coil.
Take the spark plugs out to facilitate kicking.
Hi,
I have found that the Boyer will fire the plug when the ignition is switched on and off. Also, the only time I have had a problem with a Boyer was due to the wires from the pickups to the black box had no continuity. Try bypassing/replacing these.
Dave.
Thanks Dave, I will double check that wiring but I don't think thats the prob as the test where you disconnect them and touch the yellow/Black and white/black wires together to create a shark, bypasses them.
In the past I too noticed a spark when turning the ignition on and off but not now. Reckon it's toast. Guess I'll send it back to Boyer and get it checked out. Weird to blow a coil, a Boyer and 2 plug caps at once though. Still not sure what's going on here.
Thanks again Dave.
Thanks too Rhyatt. That's a good test, I will try it. I'm fairly confident that will be ok though for the reasons I gave above.
I'll get it sorted soon
Cheers Glenn.
OK, after further testing It turns out my method of testing the Boyer was wrong because I didn't earth the positive coil terminal. now that's done the box sparks fine. However only 1 coil is working.
Current working theory is that the bad starting was due to the incorrect plug caps and the current non starting is due to a failed coil. New coil on order, lets see what happens when that arrives.
Cheers Glenn
Glenn,
I know nothing about electronic ignition, but you seem to be getting some good advice there, and are on your way to sorting your problem.
However, referring to your original post, I have always found in practice that all British motorcycles require a slightly different starting technique, and you have to discover which technique is best for your motorcycle.
I would dispense with resistor plugs and caps. That will eliminate any problem with them.
If you fit a pair of Neons to the plug leads, then you will be able to see that you have a spark while kicking.
If you kick it a few times and then remove the spark plugs, you will see if they are dry, slightly wet or soaked. You will then know to tickle it more, less, choke or no choke etc. You could even try starting it with the petrol tap closed.
If you can only start it with the throttle wide open, this indicates an overly rich mixture. If it will only start with the throttle completely closed, it indicates a weak mixture.
If it's weak, this may be due to a worn inlet valve guide. To check, spray the guide with spray grease. Also you could apply some oil the carburettor flange to temporarily seal it.
It's looking like the coil and resistor caps are your problem, so forgive me if this is not relevant, and I'm telling you stuff you already know, but it might be useful to others.
Hi Glenn, there's some cheap Chinese coils on the market which aren't really any cheaper from a good PVL one. Another good coil is the trispark ones. These are still oil filled.
I had a pair when I first built one of my A65's. It failed in less than 300 miles.
Thanks for your comments guys.
I went with another lucas coil so they're goth the same. Lets see how long they last. If they fail again I'll look at the trispark. I did put non resistor caps on in the end for the reason Steve mentions and.......TahDah! it starts 2nd or 3rd kick. problem solved. I'm hoping I can twiddle a few things and perhaps my starting technique now and get it starting 1st kick but for the moment it's fine. Many thanks for your help, much appreciated.
I have 2 more problems now. The tyre on the front wheel does not sit properly and when I get beyond 30 mph it's like riding a jack hammer!! I' put on a cheap Pakistani copy of a TT100 on and also the tubes seem to be very porous, going down in a month or so. The bike has been under construction for a number of years and the tyres have gone flat a few times. maybe that has popped it into the rim. I've tried to pop it back out a few times but no luck. I'll take it back to the fitter and see if he can sort it.
The other problem that I may need some help on is, I suspect I have a porous cylinder block. I'm going to take the head off and see what I can see. I'll post a new thread if I can't find the problem. I read a thread from someone who had exactly this problem in this forum a few years back so I'll reread that.
Anyway for now thanks again for all your help and ride safe.
Cheers Glenn
These plug caps are such innocent things but get overlooked in diagnosing running and starting.
I'm helping a pal with his Japanese 4 cylinder currently, with the long ngk caps.
2 outers were completely open circuit with my meter and 2 inners were really intermittent with circuit.
They were meant to be 5k and for 6 or 7 quid each sorted.
The spark had been a feeble yellowy orange and not a healthy blue crack.
And they're so simple to check.
If your multimeter is self-ranging all the better but if you have to select scales then try bigger and bigger ohms scales until you have reached the highest.
Thanks Rhyatt, yes I discovered how to measure the resistance during the process of figuring this out. Good old Mr Google! Good that you've spelt it out here though for those that don't know.
Cheers Glenn