I have a 86 TRX 250r and want to put a 87-89 crank in it because it has a 5 mm longer stroke. I am getting sick of having my budy with and 89 get out of the whole quicker. Can I use my cylinder or do I need to change out the top end?

Please help me go faster.

 

One of my friends did that on his 310 w/o having to change anything

 

If you use a 87-89 crank. Build a spacer plate motor. Get the plate & studs from Nacs racing around $60.00 and use the 86 piston. The money you save on the 87 crank will buy the spacer kit.