My 2002 blaster has always made a rattling sound, or a tick or a slight knock however you want to describe it, since the day i got it a few weeks ago. The noise gets louder the lower the rpms, like if i am bogging out in the snow barely keeping the engine running, the sound it at its loudest. But then normal cruising down the road or wide open throttle the noise is nowhere to be heard. My 2 friends have blasters also and both of theirs make noises too. My blaster always starts 2nd kick with full choke when overnight cold and always 1 kick when warmed up and it will idle all day long no issues. As far as i know my engine internals are stock. The engine seens to have great compression, but when you crank it over with your hand and listen, on the compression stroke you can hear a tick sound but it does it real quick and doesnt come back till the next revolution (when doing it by hand) On the outside my quad is bone stock. Except for an FMF silencer and fatty pipe. ItsOil injected (yes it works), stock airbox lid, TORS is still on the carb and the carb is stock too.