98 Polaris having compression problems

[MARIO560377]

Hy. can please somebody help me, i have a 1998 Polaris 500 H.O sportsman 6x6. the engine won't turn over unless i remove the spark plug. the engine creates to much compression for the starter to turn it. is there a compression release valve or other component that isn't working properly

[cheriah]

I have the same problem with a dirtbike I bought. High compression is from carbon build up on the piston and in the combustion chamber, check there. Polaris 4 strokes have a automatic decompressor that opens an exhaust valve slightly when cranking with the starter to ease starting but will affect your compression readings with engine cranking speed. Test your compression with a good tester that threads into the plug hole, not the ones you push and hold by hand, and see exactly what your reading is. If you get inconsistent readings, do a cylinder leakage test instead to see if it is your valves or head gasket just make sure your ignition is disconnected or kill switch activated while testing. If all checks out good there, it could be damaged decompressor or exhaust cam lobes...I don't have a 4 stroke but this is what I did on my 2 stroke and I ended up replacing the piston and rings and decarbonizing the chamber....:wink:Good luck!

[MARIO560377]

Thanks will do tests and if needed will change deconpression valve i'll keep you posted