My 01 400 explorer has a nasty habit of loosening the rear chain by itself. It seems to happen mostly after runnig down whooped out railbeds at high speed. Are they known for this and is there a fix? Thanks for any info.

 

Get a chain tensinor for HPD for it will solve your problem.

 

My '01 Xplorer does the exact same thing. I adjust it to what my manual says it should be and it still loosens up. The chain doesn't seem to be stretched out either. I think I'm going to end up doing what x_scrambler3 suggested and get a chain tensioner.

 

Chain adjustment on a Polaris is a simple thing. Once you adjust the chain and tighten the bolts there is NO WAY it is going to move on it's own no matter how you ride.

The chain wears and it needs to be adjusted over a period of time.

Adjustment can vary from wear on your rear axle bearings and swingarm bushings.