My 02 scrambler started knocking when I first crank it up but quickly stops after a few sec. it sounds like its in the top end but im not sure... Its a 400 2-stroke is it mabie an early warning sign that it needs to be rebuilt or how will I know when its time?

 

i know my top end needs to be rebuilt i have a 2000 tb 250 and it knocks from the top end all the time

 

Polaris02, how many hours would you say you have on the wheeler? The 400's are not as noisey as the 250's usually. A little piston rattle is OK, but if it gets to the point where you can hear it good all the time, then get rid of that cast piston as quickly as possible. It will eventually break and lock the motor up.Bubba

 

Like Bubba said a little piston slap is normal. You can definatley hear it more and louder on the 250. You will also notice it more when the temperature drops. As long as your jetted right you should be ok. If the knock never goes away then it is time fore a wiseco piston. What Polaris02 is describing sounds very normal. And for BADASSS250RIDER, I have never heard a trailblazer that didnt knock. They do not have a counterbalancer in them and the clearance is not very tight on the piston. This is normal but would suggest if you do some mods then go with an aftermarket piston. This will quiet is down greatly but not totally take care of it. Thats just the way the motor sounds.

 

i am going to rebult the top end and get a rcr stage 1 kit then im going to sell it and save up more money for a pred 500