What are you looking for, the book listed compression or the cranking compression????I think book listing depending on year's is between 9 and 10/1. Cranking compression is tricky with these motors because of the compression release. On the 09 500 we have(basically same motor as 400)tested the cranking compression to be only 60psi or so while my 850 had over 200psi. I though there was a problem and my polaris mechanic said thats normal, it would be much higher without the compression release engaged.