To check your squish, you can use a piece of solder. Take out the spark plug. Bend a piece of solder at a 90deg angle and put it in the spark plug hole. Make sure the solder is long enough to reach the outside edge of the dome of the head. with the kick starter, roll the piston 1 cycle to smash the solder. Now, you can measure the smashed solder with a dial caliper or mic to see what your squish is. You should do this at 4 to 6 points on each cylinder to assure you head in centered with the piston.... not that most can be changed.