Newbie needs help with skimming the head

Try this. Use a broad magic marker or paint that ring with machinist dye. Get a sheet of glass. About one square foot is a good size and some sandpaper, maybe about 280 grit. Lightly run the cylinder head over the sandpaper that you have placed down on the glass, grit side up. Use a circular motion as if you're waxing your car. After a couple of circles inspect the head and if there are imperfections, or non-flat surfaces you'll quickily see the high and low spots where the ink or dye was removed or is still there. You want a flat, uniform gasket sealing surface so repeat the ink and dye application and sand again. Keep doing that process until the surface is flat/flush.

Rotate the cylinder head in your hand so you don't sand in an angle. Some will tell you to remove that ring of metal and go for a flat surface across the face of the head. That will increase your compression, slightly, but it isn't necessary.

Here is some discussion on 'lapping' the cylinder head > http://www.google.com/cse?cx=partne...earch.php?searchid=1424503&ss=5828j2240606j21

You can check the gasket mating surface of the cylinder using the same method described above but you'll need to remove the cylinder from the engine case. If you do that make sure you know how to reinsert the piston/rings when you reassemble things.

Tom

What, do you not understand?
Tell us a little about yourself and your motorized bicycle. Maybe we can help if we know you're involved with the hobby.

Tom