Fully charged battery, WOT, both plugs out, cold.

 

@Rockymtn5280 always takes the plugs out 😄

 

Just the one causing the noise. 😏

 

Of course, to really check your engine's health a leak down test is better.

 

I take one plug out at a time. Should be done on a WARM/HOT engine. WOT helps you get there faster with less cranks, but you don't have to WOT... It'll just take longer to get the needle to stop if you don't open the throttle.

 

Compression test warm. Cylinder not being tested spark plug out. Battery fully charged. WOT.

It also depends on the reason for the test, but I would do a regular and a wet compression test and a leakdown test as well if the compression seems too low. That gives me an idea of what is wrong.

 

Leak down.

 

I do a hundred compression test every year on Rotax engines. To me and most experienced mechanics a static compression test is very poor for diagnostics and finding issues. A Differential leak down test is far better and not hard to do. Use 80 psi test pressure, but you will need a differential pressure tester. It’s not expensive and someone may have one to borrow. You need to remove both plugs. Set a cylinder at TDC and pressure test each one at TDC.

 

This makes me laugh, because in aviation we joke about what a poor indicator of engine health is determined by a diff press test. It does give you an idea where air is leaking out, at least on an airplane, but tests have been done with engines assembled with no rings and once started, they can make rated horsepower. If you had a leaky valve, it definitely is a good way to validate that. If rings are bad, I guess by deduction you could determine that, but a “normal” compression test should show very low if rings are shot.

I usually use my dealer for my RZR engine work, his shop rate is less than mine.. 😂😂

Rod