Honda cb250rs big bore

[mad99mike]

Hi see on YouTube there is a video of someone fitting a 82 MM piston does any body know where these come from the only ones I found are Suzuki dr350 but not having one I can't check pin size and position to see if it's suitable also guessing crank cases need boring and barrel needs new sleeve also open up head to suit larger bore this goes out to 305cc I know a 280 conversion is a lot easier any info appreciated

[tevie54]

Hi, that video is mine, the piston is a Henry Abe piston made in Japan but these have been obsolete for many years now, Yoshimura also made them back in the eighties but these are also rare these days, I've heard the Suzuki DR350 pistons are 82mm but the pin is 20mm as opposed to 19mm on the XL. You need to bore the barrel to fit the bigger liner and also the top crank case but you don't need to touch the head. I've got a couple of these kits and found a Honda generator piston that's an 82mm bore as well but this need machining to fit. The 280 kit uses the original liner bored out to it's maximum and this does give a useful power gain but not as much as the 305.
Hope this is useful and if you need any more info just ask.
Regards
Steve