Hi All
Well, been the owner of a BSA C15 for 2 weeks and broke down twice >:(
Been on the longest ride today, the symptoms being quite clattery, losing power, then slowing down and stopping. After 15 mins I managed to get it started again, travelled 4 miles before it happened again. Engine very hot and oil smoking. So any ideas. Why is it getting so hot? and what is the clattering. Sounds metallic but wondered could it be pinking and there is a problem with the timing. Or could it be valve adjustment? Any suggestion greatly appreciated.
Pete
It's best to give the bike a thorough check out covering:
1. Tappets - check inlet and exhaust clearances
2. Contact breaker points - check condition (not burned away) and gap (15 thou)
3. Ignition timing - check fully advanced it is 7.1 mm or 33.5 degree BTDC
4. Carburation - check carb flange is flat and O-ring is ok - check jet sizes and if no air filter fitted increase main jet by 10
The problems could be caused by a retarded ignition timing or a very weak mixture. Check spark plug colour after a run - sooty means too rich and no deposits or no colour means too weak. The engines can be a bit clattery at the best of times but can be made worse by incorrectly adjusted tappet clearances.
Thanks for that
Tappets fine
Spark plug dry but black
Will check points
Timing is beyond my expertise so may have to take it to my local garage.
What I don't understand it's fine for 10 miles or so but then loses power and dies.
I would also check the coil and possibly change the condenser if it is breaking down when hot.
:) :) :) :)
Guess a check on the oil return would be a good direction/
Mike 8) 8) 8) 8)
Quote from: Sticky on 18 Jun, 2022, 17:26
Thanks for that
Tappets fine
Spark plug dry but black
Will check points
Timing is beyond my expertise so may have to take it to my local garage.
What I don't understand it's fine for 10 miles or so but then loses power and dies.
The ignition timing is fairly easy to check with a pencil inserted into the spark plug hole (don't insert too far and risk the piston snapping it in half). With bike on centre stand and in gear, rotate the engine by turning the back wheel until the pencil shows you are at top dead centre (TDC) which be when you have max projection of the pencil out of spark plug hole. Mark pencil at lip of spark plug hole to indicate TDC position.
To check ignition timing, you need to be at TDC on the compression stroke rather than the exhaust stroke with the former indicated when both valves are closed (adjusters will both have slack at this point). Rotate the engine backwards until the pencil has dropped a couple of cm. Then insert a bit of aluminium foil or 1 thou feeler gauge between the contact breaker points. Once done, slowly rotate the engine and back wheel forward until you find the point at which the foil/feeler gauge will just slide free of the points which marks the point at which the points begin to open and the spark is generated. This should occur just before the TDC mark but only just - in fact, just 0.2 mm before TDC.
This is checking the fully retarded ignition setting but is probably good enough to show if the timing is ok or way out. The best way of checking the timing is fully advanced which should occur 7.1 mm before TDC. However, to do this test you have to rotate the contact breaker cam fully CCW while doing the test which unfortunately requires 3 hands or extra ingenuity!
Once you've checked the ignition timing, the next step would be to check out the carb and fuel supply.
Sounds like the piston us nipping up in the bore.
Thanks for all the suggestions, yes, oil is returning. Spaceman, I will do that, many thanks for the explanantion. Sorry, not sure what "nipping up the bore" means.
CONTROVERSIAL STATEMENT AHEAD. DO NOT READ IF EASILY OFFENEDED ;)
Ive always like old, classic vehicles and bought this to dabble with, with the intention of possibly getting a twin in the future. But so far experience has not been all positive. Good job I still have a couple of reliable Jap bikes I can still get out and ride.
You are getting a light seizure of the engine. Often occurs nowadays as many run the mixture too rich and causes "bore wash" where the oil which would be on thd cylinder wall gets washed off by the rich mixture. Can you get your hands on a cheap flexicam to put down the plughole. Have a look at the sides of the cylinder for signs of alloy on the walks.
Where are you based.
Quote from: Sticky on 19 Jun, 2022, 12:52
Thanks for all the suggestions, yes, oil is returning. Spaceman, I will do that, many thanks for the explanantion. Sorry, not sure what "nipping up the bore" means.
CONTROVERSIAL STATEMENT AHEAD. DO NOT READ IF EASILY OFFENEDED ;)
Ive always like old, classic vehicles and bought this to dabble with, with the intention of possibly getting a twin in the future. But so far experience has not been all positive. Good job I still have a couple of reliable Jap bikes I can still get out and ride.
You are right about Jap bikes. They were far more advanced than anything we had to offer. I have 3 BSA bikes as that's what I had as a student in the 70's. If you keep British bikes, you have to accept their problems. I don't blame anyone for jumping ship to have a bike that works, doesn't leak oil and you can use. Have you seen the price of Jap classics!
Cheers CDS....makes sense. Im in Malton, North Yorks.
Adrian.....quite agree but nothing looks or sounds like a BSA twin, to me. But if Im going to spend more times mending it than riding it then I may have to reconsider my plans. It's ok if you are a dab hand at engineering but I'm not sure they are a good option for the average DIY er. But that's why I bought this. Cut my teeth, and see how I get on with one.
Hi Sticky,
Stick with it and keep asking questions. There quite a few reliable C15s about. In fact at a BSAOC event over the last couple of days one attendee had ridden from the NE to an event near Selby and would be riding it back home. A female rider used to ride her C15 all over Europe to BSAOC events.
It can be done and you can do it.
Dave.
CDS, how can I weaken the mixture then? Is it one of the screws on the carb
Cheers Dave, this did ride fine and I had a lovely ride until after 1/2h it lost power and came to a stop. Its a nice change to my other bike....Suzuki B King...Hayabusa powered naked.
:) :) :) :) :)
Its all relative. I've just read a book called "Gasoline Gypsy" its about a girl who rode a Beesa Babe(125cc) 12000 miles from Vancouver all down the west coast of USofA into and across Mexico then back into Us and up the east coast to New York. Carrying All her supplies, camping gear and an Airedale dog in a box on the back. Yep she had some problems along the way but the bike basically kept going.
I have had several Jappers and with one exception OK except Honda 400cc twin almost new late 60's I think 9000 miles on the clock----siezed solid. A fault in all of them.
My best ever was BMW 75/5 750 twin Lovely alround bike---Normal Beemer gear change???
Brit bikes??? do them or have them "done" properly and they are fine. Pay particular attention to the gaskets and don't accept even the first little dribble of oil---sort it straight away cos it wont go away on its own and it will generally get worse.
If it sounds like bag of nails--do it now---its no good saying "yeah I know, but its always sounded like that"
End of yap
Mike 8) 8) 8) 8)
It's the horizontal screw on the carb side. Before you do anything take some time to read up on setting up a amal carb. If you can get a copy of the Rupert Ratio book. Having knowledge beforehand can save a lot of money in the long run.
You really need to know if the piston has "picked up" on the bore. If ithas there is no point going any further till that damage is rectified.
Well bike won't start at all now. It fires occasionally and tries, but I guess it then floods and then nothing. If I take the head and cylinder off I presume I will see something then. If what you say has happened am I best to get it honed (is that right) some new piston rings and put it all back together. I should be able to do that but it won't be for a while. I've lost interest in it now and will get out riding the B King. Maybe later when I have got over the disappointment.
I honestly doubt if there is anything wrong with the bore and, even if there was, it would not explain why the bike is not starting any more assuming it turns over freely.
The C15 is such a simple bike, it's just a question of taking it step-by-step to work out what the fault is. If you have messed about with the carb, it's best to return it back to where you started. To change the mixture, it's normally a question of changing either the needle or needle jet or the main jet but from earlier comments on the plug colour, it doesn't sound as though there is much wrong with the mixture at the moment.
If it's now not starting, I would start by checking you still have a spark with the spark plug earthed through the engine. If you have a good spark then the problem is almost certainly carburation assuming you still have reasonable compression. One of the problems you can get with old British bikes is because of the state of the carb whose internal passages or jets can get blocked with crud over time. The other problem can be worn out needle and needle jet and a worn out throttle slide and bore resulting in air escaping past it.
I would therefore dismantle the carb and give it the best clean you can. Its difficult to tell whether or not the needle jet is worn and its sometimes best just to replace it with a new one. I would inspect the condition of the float and make sure the float needle is in reasonable condition. However, the most important thing is to check the condition of the throttle slide which should be a reasonably snug sliding fit. If there is significant sideways play in the bore then a new slide may cure that - unfortunately, if the bore is badly worn it may be a replacement carb. The last thing to check is the mounting flange and O-ring. The flange should be absolutely flat and, if not, needs to be rubbed down using emery paper on a flat surface.
Once the carb is back on, I would then check the fuel flow by taking off the drain plug and check (carefully) that you have good fuel flow and haven't got, for example, a blocked petrol tap. If none of the above suggestions gets the engine started again then a top-end inspection of the engine might then be necessary.
Thanks Spaceman
The carb I can do and will start with this. What I don't understand is why the problems that could occur with it would cause the engine to overheat. Is it because the mixture becomes lean?
If it has siezed more than once there are many good reasons why it won't start again.
Yes, but not convinced it siezed. When it stopped it wouldnt start again, but it would turn over.
Hi,
It may be possible to get an idea about nipping up by looking in the plug hole. In the shade, a small torch should light up the bore quite nicely and with the piston at the bottom most of one side of the bore can be seen.
A lean mixture will cause over heating. As the fuel goes into the engine it absorbs heat and I think that a small part of the fuel air mix is exhausted taking a some out of the exhaust. So without this the engine gets hotter.
What colour is the spark plug?
Dave.
A motor can seize,cool down and run again. If you think about it an ignition or carb setting would probably not make the engine clattery (unless you mean it was pinking like hell).
Do you know if it has has a rebore recently? It's amazing how many companies have no idea about piston clearances.
At 13.06 look what happens and re-starts a few seconds later. This is nipping up I believe.
https://www.youtube.com/watch?v=_j9mCW6xghw&t=860s
I don't think you can compare what might have happened to a 2-stroke 125 cc D1 Bantam being thrashed up a long steep hill, a lot of the time in a low gear, with what might have happened to a 4-stroke C15 being used on ordinary roads. The poor old Bantam might well have over-heated and I'm surprised he didn't seize the engine completely - the D1 wasn't designed for that sort of abuse!
Why can't you compare it?
An engine is an engine. If something is wrong you have the same result. Either could be badly recored, either could have wrong Carburton and either could have incorrect timing.
Hi Sticky,
Where about do you live? There may be someone close who is prepared to come and help.
Dave.
Well, the video was just to show what nipping-up is, that was all.
Sticky - if you live near me at Burton On Trent, I would be happy to take a look at your C15, I've had plenty of them but to be honest I haven't had a good one yet!
Sticky, When you've sorted this out you'll have a great sense of satisfaction, and you'll have learnt a lot about the bike. Stick with it! :) Phil
Many thanks for all the replies. I'm in Malton by the way.
I stripped the carb yesterday and cleaned it thoroughly, although it was mostly fine. The pilot jet did appear gummed up so that is now clear. But to no avail. There is a very reputable garage in Malton who are going to have a look at it for me as I have exhausted my skill level. Watch this space. One thing I did notice is that in my carb parts 1, 2 and 3 are missing. See photo.
The missing parts are the choke assembly. Not really needed as you can get it started by flooding the carb with the tickler. Once you've had it running for a minute or so it will be warmed up enough to idle.
Hi Sticky,
As said, the bike will run without the choke parts once warm but make sure that the hole in the carb top for the choke cable is sealed. If not then air will get sucked in causing a weak mixture.
There are BSAOC branches that meet at Yarm and Old Snydale, Near Pontefract. They look a bit far from you though.
Dave.
There may be the answer to the question if the carb top hole isn't sealed.
Ah, yes, hole is sealed. Bike is gone to be looked at by someone who knows more than me. Lets see what he concludes.
Many thanks for everything one and all. I have certainly learnt a lot even though the problem is not sorted yet.