I have a new project and would like to get some advice. Heres some background info...I have a yerf dog kart that originally had the weak 6.5 techumsi and replaced it with a mild modded briggs 8hp. It worked great but kept blowing oil from breather all over the engine and everywhere else. Then started running funny..loss of power, hard starting etc. Well, decided to check head gasket (thought it was losing compression) well not only was gasket (stock briggs) torn but pieces of it got into the rings and scored and gouged the cylinder really bad Not only that but when I bought a new intake valve a while back I never checked its length and it was not completly closing until almost TDC. All I thought was more money to sink into was not a good idea. So, after reading about those on this forum think well of the HF clones I went out and got the 11hp one as I hope will do fine for off roading. Well here lies my dilema, what mods do I need to do in order to get the most performance or do I just leave it alone stock and with this will it be ok for off road use. By the way its a two seater I am 220lbs and my son is 115lbs.