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, 20206 yr by whatmore

 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.

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

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.

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

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.