My 2-stroke experience is not translating as well as I thought it would with my first 4-stroke.

Fuel: PM 20/20 (always fresh)
Plug: O.S. F
Prop: 12X7 APC

I have the high end at 1.5 turn out. This seems to be a common setting for this engine (right?) and it averages about 10900 - 11200 rpms there, with a nice smoke trail, and excellent power. The low end is giving me some problems.

I get the engine to idle at around 2200rpm. I roll the throttle to full and back to idle, and it will hold it there. But after 20 seconds, I roll to full and get hesitation. It goes to half throttle rpms instantly, and then slowly CREEPS to full thrrttle rpms. Then when I go back to idle, it's at 3000rpms. Frustrating. This hasn't effected flight much, because I'm never at idle for more than 5-7 seconds or so, and the engine runs superb, but I've heard it should hold a perfect, consisten idle, and maybe I'm going about these settings wrong? The needle is set around 2 to 2.25 turns out, and this seems like a lean setting, but when I turn it in to 1.5-1.75 turns out, the idle creeps up, and YSDoctor says that's a sign of richness. Any suggestions?

"I turn it in to 1.5-1.75 turns out, the idle creeps up, and YSDoctor says that's a sign of richness. "

You're adjusting the wrong needle to get what you want. Read the directions that came with the engine...

The idle needle is what I'm talking about. The high end needle stays put at 1.5 turns. What other needle controls the idle if not the low end needle?

Frank,

Reread the YSDoctor: Here is a direct cut and past from the page http://home.att.net/~ysdoctor/ys.htm

LOW END

After top end is set, bring it to an idle 2,000rpm's. From full throttle set your trim so it will hit 2,000 instantly not drop slowly like 35,30,25,22, 2,000. NO it has to hit 2,000 BANG.........After about 3 seconds, the engine will start to let you know if it is to lean or rich.

If the mixture is to rich, the rpm's will start to slow down 2,000 19,18,17. Lean the low end.

If the mixture is to lean, the rpm's will start to speed up 2,000 21,22,23. Richen up the low end.

Remember, after you adjust the low end, always bring it back to full throttle and back to an idle to test your adjustments. DO NOT CHASE THE MIXTURE. make the adjustment within 5 seconds when you hit idle, Do not let it idle for 10, 20 seconds and try to adjust again. You must bring it to full first and back down to check the adjustment.

After adjusting the low end, it should idle at 2,000 consistently for about 20 seconds.

After the 20 seconds, bring it back up to full throttle by rolling the throttle stick up. DO NOT NAIL IT TO FULL !!!!!! THROTTLE............ Roll it. It should take you just over 1 second to go from idle to full.

Another trick to test if the mixture is correct is to pull off the fuel line at the carburetor at idle. There should not be any fuel coming out of the fuel line. If you do, you are still to rich. This is best done on the bench and not on the plane.

End of paste

Also remember that the idle needle is an air bleed, so opening further means leaner.

Dale