With the engine cold, first you have to remove the seat and fuel tank. Then all you have to do is screw the threaded end of the gauge into the spark plug hole until it’s tight (you have to remove the plug first, obviously). Then hold the throttle wide open to guarantee the engine receives enough air, and then turn the engine over using the kick-starter. You will have to give a few hard kicks before the needle stops moving. When it does, you’re finished and you can record the reading. Be sure to let the pressure out of the gauge before you remove it via the relief valve on the side.
It’s good to periodically check this “static compression” of the engine at several times during the riding season. Checking this is like checking the blood pressure of an engine; it gives you a quick overview of the wear in the cylinder. This reading varies with the modifications to the engine including squish clearance, volume of the cylinder head, head gasket thickness, deck height, and exhaust port timing. I believe a stock Blaster in good shape should read 125-130psi. I have also heard that some gauges can be inaccurate, but as long as you use the same gauge every time, the internal wear can still be accurately measured.
