I have a Suzuki lt250 that has a 1985 Honda CR500 motor installed. I bought the bike last year from a guy. Second day out I burned a big hole through the top of the piston. Anyway I rebuilt the motor and jetted it. It was running way lean. I took the cylinder off this winter to get it polished and the new piston still looks good. No signs of burning or pitting on the top of the piston. It is bored 80 over next time i have to resleeve. I want to know if I should run race gas straight, a race gas mix or what other options to make sure I dont burn a hole in the piston again. The compression is about 160 psi. It has been running great and no signs of wear on the piston but I dont want to go out this summer racing up sand mountain and blow it up again.
any comments would be greatly appreciated
also it has the stock lt250 radiator. Is this big enough to cool the 500?

 

Race gas wont make a Lean engine less likley to burn down It is mainly run to alow the running of advanced timing and higher compression. That being said 160 is pretty close to needing race fuel. If you have ran it a substantal amount of hours since your first rebuild and there is no sign of Detonation. I would say just go and have fun dont worry about it.