Darren,

My YS experience is still pretty much limited to engines that don't have any problems and unfortunately it sounds like yours definitely has some issues.

It sounds like yours is running rich no matter where the high speed needle is set. Opened up fully the high end is adjusted pretty much like any other 4-stroke. Except I've found on a YS that if it is too rich it will tend to load up and sputter a bit. The high needle on my 91AC is exactly 1-1/2 turns out. If your engine has the wrong needle valve you should be able to get the correct on from from Central Hobbies.

The idle adjustment on my 91 has no affect on things except at when the engine is at idle, and it is not a very sensitive adjustment.

The regulator adjustment controls the spool-up mixture. Its not all that sensitive an adjustment either, so don't be afraid to play with it. On the rich side the engine will put out a ton of smoke when the throttle is opened up. Closing it off reduces the smoke. But the engine should run OK as long as it is set close to right. Start with it flush to the body.

I think that the plunger/regulator on my 91AC sticks a little sometimes when I haven't flown the engine for a while. It loads up, coughs and sputters. But once warmed up completely everything clears up and there are no more problems for the day.

Walt