You will need to spin the engine over with the gauge installed and the throttle held open.

Right now 30 PSI means nothing. Was the engine dry? Was the engine warm? Was it spun over on a starter box or did you just slowly pull the starter rope? What position was the throttle? All of these things can change the compression readings.

The main thing you will find over time in using a compression gauge on one of these little engines is that what ever you do, you have to do it consistantly.

When I was doing a bunch of testing several years back I liked a cold engine, two or three drops of oil on the piston and then spin in over for a few seconds before installing the gauge. Then I spin it for a second to get my reading. Throttle held open.

Ed M.