I need the proper procedure to check the engine compression on a '00 Scrambler 500, I only got a reading of 33 psi and then 38 psi after putting a bit of oil thru the spark plug hole...the engine was cold (65 degrees out) and I cranked it over with the throttle at wide open. The engine battery is only about 1 1/2 years old. Just need some help to verify these readings as they seem incredulous...

 

I had sunk mine and couldn't get it to start for nothing. I did everything I could to clear out any water and still nothing. I assumed that I damaged the engine so I did a compression test. Same as you 30-40 psi. I pulled the head thinking there was internal damage and found some water still in the cylinder because of the angle the cylinder is at. Cleaned out the remaining water and checked everything out. Everything looked good so I reassembled with a new head gasket. Did another compression check and still the same 30-40 psi, but when I hit the key, it started right up. The only thing I can figure is that the cam is ground with decompression in it so the motor will start easier. My runs great so once it is running, it has to have more compression than that. Looks like you might have to back off the rocker arms so the valves are not opening at all to get a good test.

 

Yeah that's what I'm suspecting as the Briggs & Stratton engines have a similar cam design to blow off compression to relieve stress on the starter or person pull starting the engine. But I'd like to know if there's something in a service manual on how to check it more easily than pulling a rocker off-I'd like to know that procedure, lol. Anyways thanks a ton for your experience easystroke...