bobtlr Posted April 20, 2010 Report Share Posted April 20, 2010 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 Quote Link to comment Share on other sites More sharing options...
piston197 Posted May 27, 2010 Report Share Posted May 27, 2010 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 Quote Link to comment Share on other sites More sharing options...
bobtlr Posted May 28, 2010 Author Report Share Posted May 28, 2010 can i just fit one of these or do i have to balance the engine after fitting this? Quote Link to comment Share on other sites More sharing options...
piston197 Posted June 4, 2010 Report Share Posted June 4, 2010 No,balance factor same for both pistons,if you need on phone me 01989 750731,John Quote Link to comment Share on other sites More sharing options...
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