I've Had my bike(yz 125) for a year now and the motor has blown up twice now. The first time a skirt of the piston went to pecies all through the engine and the second time some peice of brass came up and sized the crank shaft. All this happend in a less then one year. I have a 1998 yz 125 with FmF pipe and silencer, Wiseco piston and hot rod kit,and Boyesen reeds.I also never fouled a plug. Could the carb. be running lean? I need to fix the problem, I don't wanna pay $700 again. Any advice would be helpful.