i need some help

[freeman79]

i have a 2002 400 and it is all stock execpt for a k/n air filter and bored 30 over just because it started smoking. but my question is when i crank it until it gets really warm it spits back through the carb and try"s to cut if off or in most cases it does cut off. what can i do or change?
thanks

[Scro]

Check your timing and your valve clearances.

[freeman79]

thanks ill do that