40.2 MM Piston. What do I bore the Cylinder too? Home › Forums › Italian Motorcycles › Benelli Motorcycles › 40.2 MM Piston. What do I bore the Cylinder too? Viewing 1 post (of 1 total) Author Posts 2010-08-16 at 7:00 am #12266 sparkplugMember Hello I have a 1970 50cc Benelli Buzzer. I need to have the cylinder bored out. The next oversize is 40.2. I already have the piston but I need to know what to bore the cylinder to. :?: Any help would be appriciatied. Thank you Randy Author Posts Viewing 1 post (of 1 total) You must be logged in to reply to this topic.