classic motorcycle forum

Motorcycle Discussions => British Bikes => Topic started by: Snooper on June 18, 2013, 12:32:51 AM

Title: BSA B31 / B33 interchangeability
Post by: Snooper on June 18, 2013, 12:32:51 AM

can a B31 Barrel/piston be fitted to an M33/B33?  would i have to change crank/rod ,head/valves ?
Reason i am asking i i cant get hold of a 500 barrel anywhere.
thanks

Title: Re: BSA B31 / B33 interchangeability
Post by: rogerwilko on June 18, 2013, 01:27:37 AM

You would lose compression using a B31 bore with the B33 head. Hang in there and keep looking. Or get a B31 head and bore the 350 barrel out to 76 mm and use a Triumph T140 piston .