My trail blazer had the same problem when i first installed the hpd pipe and muff kit. I took it to my dealer and they had to addd a new wiesco piston and bore the carb. It cost $999 for the labor alone!!!!!!!!!!! But after that the thign ran geat! It has about 38 hp and it is a 282cc! It beats stock 400 scramblers all the time!
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