This problem has been going on since I got my grizz. I found out that one of the reasons I got it was because the boot blew off the carb. We tried to rebuild the carb and broke the overflow tube off in the bottom of the bowl. So I bought a china made carb and got the same thing. Worked on the china made carb for awhile and just gave up. Bought another carb and rebuilt it and as soon as the grizz got warmed up it blew the boot of again. It will idle fine and run fine until it gets warmed up. I really don’t know what to do. dezz and keith20mm have given some real good explantions of things to do. It is still blowing the boot off the carb and intake.. Would appricate some help if possible. Thanks for the help already given and the help I will be getting. Can it be timing or valves or maybe cdi box.. Please HELP!!!