FS110 4 mix

[PTmowerMech]

Couple of questions.

I have this adjusted so that it's running good. Quick trigger response. But the head on this, which has those plastic blades, keeps turning. When I back the idle screw out very far, it'll die. And doing this while I'm also adjusting the low idle, to keep it idling. (If that makes sense). But before the blades stop turning, the engine dies from too low of idle

Is there something different about the way these heads are on a 4 mix? Or should everything adjust the same as a normal 2 cycle? If so, then I'll probably need to rebuild the carb. The low side is only backed out about 1/4 turn.

Note: I haven't checked the compression on this yet.

 

[Fish]

The clutch is stuck to the drum, could be just rusted up, or a spring broke.

 

[Fish]

Take off the front drum housing and take a peek. Looks like this...

 

[StarTech]

Yes clutch spring can broken.

But also help the tune the engine idle mixture and speed to specs per the service manual using a tach. Pretty hard to judge 2,800 RPMs by ear. You need the service manual for the 4180 power head.

If you need to replace the spring you will need a T-27 bit socket, a T27 screwdriver, an inch pound torque wrench, and a piston stop at least to do the replacement correctly or you can just guess at the specs. Note the piston stop is a M10-100. Again how to do this is in the 4180 service manual.

 

[PTmowerMech]

Took the two apart, I didn't have much trouble separating the two. My normal procedure for 2 cycle, is to close off the L to increase the idle RPM's then back off the idle screw til the engine idles, but the head stops turning.
After doing this, i noticed the L was only maybe 1/8th turn from bottoming out. So I guessing the L side is flooding.

This means a rebuild? Or replacement maybe?

 

[StarTech]

Please get yourself an inductive tachometer. Guessing at it doesn't cut it. Plain and simple.

These trimmer idles at 2800 with clutch disengaging before reaching this lower rpm.

Plus these engines are tuned at 3100-3200 max idle speed. First warm up the engine for at least one minute then you tune L to best speed and then set LA @ 3200 rpm. You may need reset LA a few times while finding L best speed @ 3200 rpm. Then you enrich L until you drop to 2800 rpm. If the trimmer head is still turning when you are at 2800 then you have clutch problems.

And there can be a problem with the carburetor but first you got to try to tune it to the above specs as you got to remove the a possible setup problem.

As far as rebuilding it cost nearly as much as a new carburetor from since both has to be obtained from Stihl if you want a OEM kit or carburetor.

 

[PTmowerMech]

Please get yourself an inductive tachometer. Guessing at it doesn't cut it. Plain and simple.

These trimmer idles at 2800 with clutch disengaging before reaching this lower rpm.

Plus these engines are tuned at 3100-3200 max idle speed. First warm up the engine for at least one minute then you tune L to best speed and then set LA @ 3200 rpm. You may need reset LA a few times while finding L best speed @ 3200 rpm. Then you enrich L until you drop to 2800 rpm. If the trimmer head is still turning when you are at 2800 then you have clutch problems.

And there can be a problem with the carburetor but first you got to try to tune it to the above specs as you got to remove the a possible setup problem.

As far as rebuilding it cost nearly as much as a new carburetor from since both has to be obtained from Stihl if you want a OEM kit or carburetor.

I got the new carb on and it does run better.

Checked out the clutch, and as you mentioned, the other problem was in the clutch. After removing the housing, and disconnected it from the shaft, one little turn of the bolt that holds the clutch to the fly wheel, the clutch sprung back into place. So removed the clutch, wire wheeled all the rusty spots, reassembled and at first, the head didn't turn. After I gave it throttle, it spun the head, but never released it after I let go of the throttle.
Took the housing off again, and just barely loosened one bolt, and it snapped back into place.
So there's something about tightening it down, that makes it stick out.
Weak spring? Or a bad washer? worn spacer?

Wait i think i figured it out. It's the bushings, right?

 

[PTmowerMech]

Turns out, it was the bushings. removed, cleaned and put some anti seize on them. Everything is working great now.

Thanks everyone.