I have an 1986 TRX 250R with blown engine. The rod bearing went to hell. I'm going to rebuild the engine myself because I'm Financialy challanged. Here are the components I have to deal with. The cylinder is in great shape and ported for mid range and top end. I run a 38mm Kiehin air striker. The pipe is an ESR TRX11 top end drag pipe. New stock ignition. Trans and clutch are perfect. Here is my question.

The 1986 runs a short stock stroke. Can I install a +4MM stroker crank and use the stock cylinder that has been ported for the shorter stroke?

Do I need to run a stroker plate under my stock cylinder if I do this and what thickness is required.

Do I have to port the cylinder for the stroke change I think it has been taken to the limit already?

Can anyone give me a list of matching components to have the correct deck height with the a stock cylinder.

Glenn

 

What I understand is you won't have to change your porting, but you will have to have a 4mm spacer plate for the 4mm stroker crank. I am not sure whether you use a 1986 piston or a 88-89 because i believe there is a difference.

 

I believe your correct about the piston because the pin height would have to be higher and the piston would have to be shorter. What I don't know is why there are (2) types of cylinders used in 86. There is an (A) and a (B). I have a cylinder stamped with a (B). I also don't know why there are like (3) different parts numbers for cranks used from 87-89

Thanks
Glenn