BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: BOB M on 25 May, 2017, 22:17:47

Title: Another question about C15 carb
Post by: BOB M on 25 May, 2017, 22:17:47
Hi

The 375/34 carb that came with my C15 is probably best for the bin! the question I'm asking is - would a 375/31 carb be ok on the C15 if I change the jets over.

Thanks
Bob M
Title: Re: Another question about C15 carb
Post by: DEREKANDERSON8 on 26 May, 2017, 08:27:58
on my list the 375/31 carb is listed for 1957-1965 bantam 175. Unless there's a difference between the monobloc 2 stroke carbs and 4 stroke ones it should be fine.
Title: Re: Another question about C15 carb
Post by: BOB M on 26 May, 2017, 18:43:41
Thanks Derek

I've just come across an Amal concentric MK1 626/R300 I used on a Royal Enfield Bullet, would this work on the C15 as well?

Thanks
Bob M
Title: Re: Another question about C15 carb
Post by: DEREKANDERSON8 on 26 May, 2017, 21:26:43
hi bob I'm no expert but would have thought 626 would work if jetted correctly but I wouldn't know where to start, with settings.

cheers derek
Title: Re: Another question about C15 carb
Post by: JulianS on 27 May, 2017, 12:36:43
The 626 is 26 mm (just over 1inch) bore which is larger than the 7/8 inch bore of the 375 carb which will probably effect tuning the settings.
Title: Re: Another question about C15 carb
Post by: Editor on 27 May, 2017, 15:12:54
Worth a try, but it may be more trouble than its worth as the 3/32" 'step' between the bore of the carb and the inlet on the head may upset the mixture.  This happened to me donkeys years ago when I pulled a stud out of my Triumph 5TA manifold (7/8"bore) and my local breaker had an 1.1/16" manifold in stock. OK, the 'step' was the other way round but I just couldn't get it to run.
If you want to try a new concentric, then a 622 is what you need.
Chris
Title: Re: Another question about C15 carb
Post by: BOB M on 27 May, 2017, 16:28:42
Ok, so maybe I'll be ok with the 375/31 carb with the 375/34 jets.