i was wondering how do u know if youre compression is low on youre atv. i have a polaris trail boss

 

By feel of the pull starter or a compression gauge. If your tuned to your bike and know how it feels then you'll know if you've lost compression. Besides that, take it to a shop and have them put on a gauge or go the autozone like I did and pick one up for around $20 or so.

 

As a rule of thumb, a 2 cycle should run about 100 PSI+ if all is right. This is just a rule of thumb, and all engines are different. My 400 runs about 110, but never checked the smaller engines.