monty348 Report post Posted December 29, 2018 Hello all, What increments in size are indicated by the letters stamped on Beta piston and cylinders? In particular the 240 TR34 or just Beta in general. Greg Myers Paradise Pa Quote Share this post Link to post Share on other sites
nh014 Report post Posted December 29, 2018 Greg, I'm not sure this is relevant for the earlier Beta's, but here is what the engine service manual for the Beta Evo series lists for the difference in size. In each case they are in increments of 0.01 mm (0.0004"). Quote Share this post Link to post Share on other sites
Bmonk Report post Posted December 29, 2018 Pistons and cylinders for Japanese MC are also classed at one hundreth of a millimetre. Quote Share this post Link to post Share on other sites
section swept 3 Trials Bikes Report post Posted December 29, 2018 Its all about limits and fits. Mass produced components have only a finite tolerance acceptable for mass assembly, so depending on quantities say 100 cylinder barrels bored to the specifications may be plus+ or minus- but still acceptable to be married up to a piston again + or - in specification. Thats the beauty of having a new piston and a rebore, the engineer will match everything closely to the specs, more accurately than at the factory. These limits and fits are the reasons some engines are noisy mechanically and others are quiet when new. Quote Share this post Link to post Share on other sites
