Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Cough and stall

Hi Douglas, apologies for any confusion.

The Tb-0100 would replace the paper filter elements that come in the pancakes with the threaded piece and top and bottom plate. Such like fitted on monoblocks and Concentric carbs.

Ok, I know the ones you mean. If there was room I would have fitted one of those to mine. Unfortunately there is less than an inch between my carb and the airbox🙁

I'm surprised that more bikes don't catch fire. A start procedure that involves making the carb overflow and leak petrol onto a source of ignition, the magneto is far from ideal.
BSA must have had a bike catch fire as they decided to fit a drip deflector on the A7 and A10

And how many riders back in the day had a lit ciggy on when tickling those carbs?

As Koan said, the air filter did badly affect higher rpm and also to some extent the mid range. Seeing as the carb is all standard, I can only assume BSA fitted a very free flowing filter as standard. I have removed the filter and she now revs cleanly right up to high rpm.

The 30 pilot jet had a similar affect to the air filter. I know the carb tuning charts show that the pilot jet has zero effect on wide open throttle, but I have to disagree strongly with that. I have messed around with pilot jets on several Bantams and they always have an effect on every part of the rpm range. The 30 pilot today had quite a significant effect at wide open throttle. It would not rev out, (felt like a rev limiter) and actually started to bog down. I replaced the pilot with the standard 25 and now she revs cleanly again.

With the air filter and/or the 30 pilot fitted the cough and stall was improved a little, but as I've said above, the rest of the bike was ruined.

So it looks as though whatever I do to alleviate the cough and stall, problems turn up elsewhere. I'm sure in the hands of a better carb tuner than me, this could be sorted, but for now I'm just going to live with it.

I've been talking to a guy that knows a good bit about tuning racing Bantams and C15s for trials, and he has advised that I should get that scoured inlet port sorted
(back to standard) before trying anything else. So I'm going to use the bike for this season as it is and get the head and barrel off in the winter to try and sort it. I will revive this thread if I ever make any progress, but for now I'm afraid I'm done. My brain can't take anymore.

Thank-you to all that have taken the time to help. Much appreciated.

Long thread, didn’t read, but if we’re talking about those BSA/Triumph pancake air filters with paper elements, I gave up in them a long time ago. Obviously restrictive and prone to cracking in the front plate, through vibration.

That's exactly what I have Quinten.

Mine is 3 metal plates and one piece of very thin cloth.

I separated the parts and just used the thick top plate with a circle of Ram-Air filter underneath. Turned out to be way too restrictive.