Is it possible to get hot cam for a Kohler Command Engine?

I have a Kohler Command 11 ( Kohler CH11) single cylinder OHV and i was wondering if i could get a hot cam or adjust the timing so that i could get it not to back fire and run better at high speeds! where could i get a hot cam for it or how would i set the timing to do that???|||If it is back firing and not running well at high speed then either the carburetor is dirty and plugged up or you have burnt valves or both.