Hi I have a problem with my blaster. Maybe 10 gallons of gas ago the motor was rebuilt. New piston rings top end bearing and gaskets. The bottom end bearings seemed fine. The problem is when riding it sounds fine through the rpm range but when you get it high in the rpm then let off the throttle there is a distinctive knock. It will knock 4or5 times then it will be good till you do it again. The noise kinda wories me that it might be detinating but its not really a pinging sound. The plug looks good with just a little black carbon, it has good throttle response and compresion. So any input would be much appreciated thanks.

 

Did you use wiseco pistons in a stock cylinder or did you get it honed?

 

The cylinder was bored 40 over and yes i used wiesco priston and rings. I have already adjusted the carb for proper flow. What do you think it is?

 

The knocking could be your chain reversing directions and you just never noticed it before. Unless it is really loud or the machine has a noticable difference I wouldnt worry about it.

 

Thanks for the help. I have never really noticed a difference in the performance, and its just loud enough to notice. I have had 2 strokes before but never a blaster. I have noticed that there motors seem to make some wieird noises compared to others, so its probably nothing. What do you mean though by the chain reversing directions.