whatmore Posted May 17, 2020 Share Posted May 17, 2020 (edited) hi ....im getting a rebore on my yamaha ty 250 mono could anyone recomend what pistons are available and what modifications if any do i need to do to make it compatible....Thanks for any replies. Edited May 17, 2020 by whatmore Quote Link to comment Share on other sites More sharing options...
lineaway Posted May 18, 2020 Share Posted May 18, 2020 You will have to call around yourself to see who has what. The Yamaha Tri Z 250 piston was a pretty close match. Wiseco pistons offer quite a range in over bores. Quote Link to comment Share on other sites More sharing options...
feetupfun Posted May 18, 2020 Share Posted May 18, 2020 YZ250 piston but you need to make mods to the shape of the crown if you want to replicate what the original piston crown looks like. Here's a photo I found on the web that shows what I'm on about Quote Link to comment Share on other sites More sharing options...
rotors7 Posted May 18, 2020 Share Posted May 18, 2020 I remember having a John Shirt 270 conversion / rebore. For me, it was a major improvement in the engine department, a bit more torque and still a nice smooth power delivery. Just a thought if it's still available nowadays. Quote Link to comment Share on other sites More sharing options...
guy53 Posted May 18, 2020 Share Posted May 18, 2020 Piston are rare, I've looked around for one a few years back and found a 3rd os. By the time I received it I had sold the bike. It was expensive ( $200.00 us ). Guy Quote Link to comment Share on other sites More sharing options...
thai-ty Posted May 20, 2020 Share Posted May 20, 2020 Try CTC, Cambridge Trials Centre in the UK, its where i bought my ready to go Wossner pistons a year or so ago. Top notch quality. 1 Quote Link to comment Share on other sites More sharing options...
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