Idle adjustment problem - Pro Mac 1000

[Catnap]

When I adjust the idle on this old saw so the chain stops it stalls out. If I raise the idle slightly the revs eventually pick up to the point that the chain starts to move. I know at idle the chain should not move and with 100cc and a 28 " bar this becomes even more important. I just can not get the saw to idle as it should. As I said this is an older saw and I am thinking maybe the carb diaphram or something may have gone bad. The revs pick up like when the tank is running empty and sounds like it's running lean. Can someone help me with what they think this could be?
Thanks in advance for any ideas.

 

[Jacob J.]

When I adjust the idle on this old saw so the chain stops it stalls out. If I raise the idle slightly the revs eventually pick up to the point that the chain starts to move. I know at idle the chain should not move and with 100cc and a 28 " bar this becomes even more important. I just can not get the saw to idle as it should. As I said this is an older saw and I am thinking maybe the carb diaphram or something may have gone bad. The revs pick up like when the tank is running empty and sounds like it's running lean. Can someone help me with what they think this could be?
Thanks in advance for any ideas.

Sounds like you're on the right track with the possibility of needing a carb rebuild. Your clutch may also have a worn spring that needs replaced. Can you move the clutch drum back and forth? Check that drum bearing as well.