I decided to take of the head of my mitsu 49cc and guess what? It has a lot of carbon deposits on the top of the piston... Normal? Also, I can't get the head to go back on - should it be very hard? I'm not using a ring compressor, should i be? (don't have one ) Rings appear to be OK, and the cylinder wall is in pristine condition (looks new, and it has almost 1500 miles on it :O). What will make getting the head on easier, and how do I clean up the piston?