BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: chrisgoodwin on 20 May, 2017, 17:55:00

Title: '49 B31 Carburetor
Post by: chrisgoodwin on 20 May, 2017, 17:55:00
Hello BSAers,
I'm in the process of stripping my B31 for a full rebuild, just taken the carb off (Amal 276), and it's looking quite tatty.
However, along the way I picked up an Amal 289  - its stamped 289G/1A1 and it is in very good condition.
My question is can I replace the 276 with the bright and shiny 289?
Title: Re: '49 B31 Carburetor
Post by: JulianS on 20 May, 2017, 18:22:05
The 289 series is the next body size up from the 276.

I think the 276 went up to 1 1/16 inch bore and the 289 went from 1 1/8 inch bore.

If it is 289G /1AT then it is a 1 1/8 bore carb with a 7 degree float chamber originally fitted to some B33, M33 B34 models.

It might be to large bore for getting the best from the B31 (which had a 1 inch bore carb), and you might need to change jets etc, but no harm in trying it.