My friends blaster will only start if it is jump started, and when it finally starts it will have good bottom end but then anything over half throttle will hesitate,cut out, and bog extremly badly. It is pritty much stock. The carb. has been cleaned out and the jets arnt loose or cracked. We changed the plug at least 15 times with diffrent gaps and types, but still didnt do much. He was using really bad type of 2-stroke oil, and after we changed it to redline it helped alot but still dosent have it.

What do you guys think could be wrong with it?.

 

Try putting in a new top end along with new gaskets and once you find a good oil stick to it