Got a 250 arctic cat. Sounds like something is rattling all over when it's running. She's lacking power. Got a little smoke going on. I've torn into the top end and everything looks brand new exept from the piston and valves. Any ideas as to what could be causing all that rattling?

 

unless you do a compression test looking at it is going to tell you nothing... If it is smoking and lack of power i would suspect low compression and possibly valves out of adjustment.. Rattling i would suspect clutching is dirty or rollers are warn out

 

Ok thanks I'll look at adjusting the valves again.