I have a 91 250x with a 85 350x motor in it. I am looking to possably put a high conpression piston, mid range cam and of course springs and valves. I have heard horror stories of the piston smashing the valves. What is a good combination? Also is there any differance from 85 350x to a86 350x motor?

 

Hey dude...
I've got the same bike, '91 250x w/'85 350x power plant. I went mild-Wisco 10.25/1 piston,had the valves redone and replaced the valve seals. The 350x engine is bullet proof. If you used to the 250x power,wait, the power out of the 350x incredable. No more getting a run at the hills and down shifting, hoping you'll make it. Just stop at the bottom,look up,and hammer down!!!You'll eat that hill for lunch!!!

 

Well guys I have decided to buy the 12 to 1 wiesco piston the white bros mid range cam new valves the spring kit timeing chain gaskets etc.
I will let you know how it works out.