BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: WINDSWEPT on 10 November, 2017, 19:03:24

Title: B40 c15 carb incontinence!
Post by: WINDSWEPT on 10 November, 2017, 19:03:24
Hi folks, I'm pottering around on a B40 with a c15 engine, which is how it was when I bought it. I'm having problems with the monobloc carbi every now and then it dies while on the road as if running out of juice. Sometimes it pees petrol out of the tickler valve, after a while all is well and off we go.
Today it did all the above but wouldn't go again until I had took the jet out and blew through it, then managed to get home (6 miles)
I took the carb to bits and found the slide to be scored quite bad along with the bore, is it possible to polish these out?
Last year I fitted a new float needle and seat with a rubber tip which was supposed to stop the float sticking. The plastic float could be sticking on the carb body and flooding until it runs out the tickler hole?
Any help would be much appreciated as I want to keep running it through the winter months.
Thanks.
Title: Re: B40 c15 carb incontinence!
Post by: JulianS on 10 November, 2017, 19:33:41
The fit of the slide in the body is important for good running. Both slide and body wear and the bodies are often found to be distorted due to overtightening the fixing nuts.
 
On the flooding - when you fitted the needle seat did you fit a fibre washer between it andthe carb body?

If yes then you need to remove it the, original monoblocs did not need a washer here. Only the new series need it, they have a recess machined to accept it. Fitting one increases the float height and can cause the tickler to touch the float and stop  the needle sealing on the seat.
Title: Re: B40 c15 carb incontinence!
Post by: WINDSWEPT on 10 November, 2017, 20:37:03
Thanks for the reply, I seem to remember the washer not being there but will check. Will a light polish of the bore and slide help\make things worse?
Thanks again.
Title: Re: B40 c15 carb incontinence!
Post by: JulianS on 10 November, 2017, 21:08:44
Depends on the condition. Fit is important. Poor fit equals poor running and makes it difficult to tune.
Title: Re: B40 c15 carb incontinence!
Post by: WINDSWEPT on 10 November, 2017, 21:43:02
Rats! Oh well . just seen the price of a new one on tinternet >:(