Greetings! Anyone know the compression test range on a 02 500 HO? Buddy of mine turned his over in a deep hole this weekend and the airbox got full of water, I didn't go on the ride but I do know he did not pull the sparkplug and tried to start it....I went to check it out today, I pulled the carb and cleaned it,oil looked fine with no sign of water,exhaust is clear,the owner said the plug had what looked to be mud on it, it fires but wets out the plug. I'm thinking the cylinder/rings suffered some damage and there is a loss in compression but I might be wrong. Next step is to check the compression, need to know the acceptable range

 

guessing around 135 psi would be a good range. did you check and drain the base? it could have filled up w/ gas when it was rolled over. very doubtful any damage would have happen to the rings/piston from spill. imo

 

Normal compression range on the 500 is between 55-90ps or so with some getting a little higher. This is due to the decompression device on the cam. If you can get it running,I'd burn a cheap oil and filter change to see if you can salvage it,drain it out and put the good oil in.

 

Thanks Guys!

 

They have a auto decompression system so they do not show high numbers on a tester.

 

oops o was thinking of the 2 stroke lol my bad

 

Well compression is at 28...

 

Sounds like time for a top end rebuild.

 

Yep, not a lot of compression,getting all the mud off for a clean tear down,hopefully we can get the head and jug to the machinist by the end of the week. Looking at the Wiseco kits on Eb.y I come across a kit that comes with a cylinder for $299 but not sure about the quality.

 

Check the cam.Just pull the cam cover off and check the lobes and the compression release detent lever and spring to eliminate it first.