renegade issue this weekend

[rtrev]

Borrowed the sled out this weekend (06 renegade 600sdi) I was told that now, when it warms up, it wont go over 30mph. No warning lites are showing up on dash. Scored cylinder? Bad air box sensor? I heard both of these. guess it happpened after some high throttle powder riding. Any ideas out their? Thanks

 

[jimfsr]

compresssion check! does reverse work ok? Usually the first sign of weak comp. no reverse. Definately sound like its running on one cyl.

 

[snowbuff]

Bad belt? Something broke in clutch?