tri z is being difficult

[TRI Z Racer]

Today i went riding hard for the first time since i broke it in, once it gets hot it will only run for like 5 mins then it will bog down like its out of gas and stall. i can let it sit for like 5 or 10 mins and it will start again, but only if i choke it. what could this be, my friend said i should run a hotter plug, would this make any difference? Also my silencer has no packing left in it, should i repack it, would it make a difference in performance? Any help would be greatly appreciated

[TimSr]

Pull the gas line off the carb, and kick it over. Each time you kick, gas should come gushing out. If its not, start tracing backwards, paying close attention all shoutoff valves, then the fuel pump. If gas does come out, you need to check the float setting in teh carb, and make sure the float needle is not stuck.