String trimmer idles fast

[dennis]

Trimmer....Homelite 01-98, UT20680, Ser. HT0051254, Carb Zama C1U H39 79A

The trimmer idles too fast, even with Idle speed screw all the way out. The throttle lever closes all the way. The hi speed is a fixed post, and I have tried adjusting lo speed mix screw, but head still spins (both mine and the trimmer). Any suggestions?

[bgsengine]

you got an air leak somewhere

[KE4AVB]

Of course the head still spins; ITS direct drive, no clutch.

The only way to stop head from moving is to stop the engine.

[dennis]

Yes, the head spins, but the rpms seem way to high, even with idle screw out. Any idea what the idle rpms should be?

[bgsengine]

Yes, the head spins, but the rpms seem way to high, even with idle screw out. Any idea what the idle rpms should be?

2500-3000 around there

[KE4AVB]

Once air leaks are ruled out. Then first before trying one the following is to check the metering lever height it might be too low and the engine is running. But this won't be the case if you are able to lean the mixture out.

May need to pull one of my tricks out of the hat. That is soldering the air bleed on the throttle plate if no air leak can be found. Another trick I need to use on some Stihls is to run them slightly rich at idle.

[dennis]

Thanks for the info bgsengine and KE4AVB. Will check it out.