ys120sr wont rev past 1/4 throttle

[I_Bent_It]

Last night I got my YS120SR running, but it has no power. Running 30% Cool Power with it. It revs up to about 1/4 throttle, and sounds very choppy. It won't rev any higher though about about 1/4. I can see the servo arm moving, but I get nothing more out of the engine. I've tried going in, and out on both screws. Anybody have any ideas?

[Ukhan24]

Ys120"s don't like 30%. I would try 15%

[I_Bent_It]

It ran fine on 30% last week so I know that's not the issue.

I do notice that if I put it on an idle up on the ground, and give it some negative pitch, to put a load on the engine, it revs up higher, much smoother. Make's me think I'm running rich. Anyone have any ideas?

[itbvolks]

Ummmmm - reset the needles to a safe starting point and verify the carb is being pulled open properly to start with......

[I_Bent_It]

Originally Posted by itbvolks

Ummmmm - reset the needles to a safe starting point and verify the carb is being pulled open properly to start with......

Like I stated earlier in the thread, I've tried numerous needle settings, richer and leaner, and I can see the throttle being moved

[Steviepoo]

Are you running 30% on one head shim or two?

[I_Bent_It]

One shim. Please let me reiterate before you say to add another shim...it ran fine last week on the same setup. Still has great compression...just kind of spits and sputters and no rpm increase after 1/4 throttle

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[daisydog]

I know it seems obvious, but I'd replace the glow plug. Sometimes it gives you troubles that don't make sense. If I ever have issues tuning or hard starting I change my glow plug and have had success.

Other than that I'd check my fuel lines for cracks or a hole.

Good luck.

[itbvolks]

Sounds like an air leak.

Check your supply/return lines for cracks or splits.

[I_Bent_It]

Fixed. Inadvertently turned the gov. On at 8%. It revd up when I loaded it because it was bogging ;-)

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