April 20, 201016 yr Hey i have a Bsa B40 GD now but i would like my bike to be a bit more nervous and powerfull. the bike has a standard piston for now but i would like to know if there if a piston available that gives higher compression (from a road version of the b40?) and can i just change my piston ( it has a flat surface) for a high compression piston or do i have to balance the flywheel and do other stuff to my engine? best regards bob
May 27, 201016 yr Basically there were 2 pistons used in the B40 standard ratio 7:1 and higher comp version 8.75:1,the higher one now seems to be favoured by the more experienced(and more aggressive riders),i still have about half a dozen of these all 1/2mm (+020) oversize,can deliver to the bonanza if anybody wants one,the low comp piston measures 1.608" from centre of pin to top,high comp piston measures 1.801" for identification. Pistons i have are all genuine BSA
May 28, 201016 yr Author can i just fit one of these or do i have to balance the engine after fitting this?
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.