If it was cycling regularly, about 5 seconds per cycle, that is called hunting and is caused by the governor trying to compensate for lean mixture. You just need to adjust the mixture screw toward richer mixture - probably about a quarter turn anticlockwise. However, check your starting point: the mixture adjustment (the big black knob) should be two turns anticlockwise from all the way screwed in. Be gentle when you turn it all the way clockwise or you'll ruin it when it bottoms. Count the turns when you screw it down, and see if it is currently two turns open, or something close to that. If it has been running at two turns, you still need to open it further and retune it, in case there is some junk under it - it will probably flush itself out. With the engine running, turn it anticlockwise (that is, unscrew it) a bit and see if it stops hunting. Then adjust it for best running, and when you find that setting, make it a bit richer ( perhaps an eighth of a turn anticlockwise) but not enough to really foul it up. 2 strokes like to be a bit rich: you want it to be tending to four-stroke at high speed with no load, but you don't want it so rich that it slows down noticeably.
If you want to check the float needle, after you measure the float height, turn it back the right way up and see if the needle follows the float arm when it drops down. If the needle is sticking, the float will drop but the needle will lose contact with it instead of following it down all the way. Note Page 4-6 of the manual warns that this may happen if you don't have the spring-clip properly hooked around the float arm.
If that isn't all clear to you, just tell me and I'll try to do better.
Last edited by grumpy; 23/12/10 08:58 AM. Reason: Add comment on page 4-6
