BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: Tigerfeet on 20 Apr, 2026, 17:09

Title: Monobloc leaks
Post by: Tigerfeet on 20 Apr, 2026, 17:09
My C15 is now a runner! After forty-six years of slumber...

I've got some petrol leaks from the newly rebuilt monobloc. Basically everywhere there is a stupid fibre washer...
(modern fibre washere - including those in the Amal kits - don't work).

I've fixed the leak from the main jet holder with a Dowty washer. And done the same with the banjo bolt. But I don't have a solution to the leaking fibre washer at the bottom of the banjo filter.  Has anyone got a fix?
 
Title: Re: Monobloc leaks
Post by: V500 on 20 Apr, 2026, 17:50
Yes, either soak those red fibre washers overnight in petrol or oil before use, or fit them and nip them up the following day after the fuel has softened then slightly.
Title: Re: Monobloc leaks
Post by: limeyrob on 20 Apr, 2026, 20:21
If its an original Monobloc it may not have a washer under the banjo filter.  There's no washer under the float valve or under the filter, only on the bolt holding the pipe union on.  The flange on the top hat is the seal.
Title: Re: Monobloc leaks
Post by: Tigerfeet on 28 May, 2026, 06:47
To close this thread off - V500 was spot on with the advice to soak new fibre washers in petrol overnight. The carb is now fuel tight.
Title: Re: Monobloc leaks
Post by: iansoady on 28 May, 2026, 10:09
I've never come across that idea before - stored for future use!
Title: Re: Monobloc leaks
Post by: cdsdorset on 28 May, 2026, 23:13
Quote from: Tigerfeet on 28 May, 2026, 06:47 To close this thread off - V500 was spot on with the advice to soak new fibre washers in petrol overnight. The carb is now fuel tight.

It may be fuel tight but if it is an earlier carb that shouldnt have a washer your float/fuel height is now wrong.