Chainsaws

Juergen,

First, The clutch is left hand threaded, which means to loosen it you will need to turn it clockwise. There is a special clutch tool for removing the cluch, and some clutches have a hex center which a metric socket will fit on, but if you don't have that, some individuals have been successful by using a thick (1/4 - 3/8)  pin punch on the center hub, and hitting the pin punch with a hammer. Be very careful Not to hit the clutch shoes with a hard hammer, or trying to pry on the clutch shoes, they are made of cast steel and they will break like any cast metal. Also remember clockwise direction to loosen.

Next, to stop the piston, and crankshaft from moving, there is another special tool called a "Piston stop" which threads into the spark plug hole, however some old time mechanics use a piece of starter rope. You remove the spark plug, then turn the clutch over by hand in the clockwise direction look into the spark plug hole and you should be able to see the piston coming up to the top. Just before the piston completely reaches the top, take a piece of 1/4" or thinner rope or starter cord maybe a foot long, and push it into the spark plug hole leaving a tail so you can pull it out when your done. Do Not use any rope that is too fiberous where the fibers will break off and remain in the piston or you will have a mess getting the fibers out of the piston, a good piece of thin cotton rope. Now continue to turn the clutch in the clockwise direction, and you should feel the clutch compressing the rope and becoming tight, Now with a tool try moving the clutch in the same dirction and it should come loose.

I hope this helps.