Checking compression

The right way to do it is to remove all the plugs and prop the throttle wide open' Then screw your tester in and crank it over. It doesn't matter if you give it 4 cranks or 6 as long as you do it the same for all cylinders. What you want to watch is that the first jump of the needle should give you 1/2 of your total compression (approx). The difference between your highest cylinder and your lowest should be LESS than 20% on a good engine.

You can also do a wet test by squirting 3-4 pumps (depending on your squirt can) of oil in the cylinder and following the same procedure.