Stihl FS400 HEad keeps spinning

[champagnecharly]

Hello,

 

I have a stihl fs400. I can not adust the L/H on carb so that the head stops rotating.. What could it be? Adjusting L/H does have a minor effect but no by any means enough to get it even close to stopping.

 

Hope somebody can advise.

 

Thanks

[Stephen Blair]

There should be an idler screw somewhere, that's the fella your looking for imo.

[champagnecharly]

Hi, Thanks.. That screw (the only screw) on the carb is exactly what i was referring to when I said the L/H.. at least that's what I think you mean and it has no difference.

 

Regards

[GardenKit]

That will be a broken clutch spring allowing the clutch to engage at a low speed.

[champagnecharly]

Thanks.. Would that be noticable?. I took the clutch off and had a gander but all looked intact. A minor amount of surface rust but fine.. I start wondering if its my throttle cable that's misadjusted.. When you say low speed I wonder if it is actually low enough.. What RPM should it be and what is best tool to test the same?

[Rich2484]

Is the cable loose when the machine is on tickover.

 

I'm thinking the controls have moved forward a bit tightening up the cable. Remove the throttle cable from carb and start it up. Will let you know if the cable is at fault as the throttle will be down to as low as it can without the cable influencing the throttle lever.

 

Basically remove the cable from the carb and see if it makes any difference. If it doesn't then the screw should be with the throttle lever on the carb. Easy to spot.

[champagnecharly]

Good plan. That certainly rules out one factor. Have done the same and it still spins. I also have the carb adjustment scew all the way in so idle is at its lowest.. but still no luck.

[Rich2484]

Then I wold look at clutch. Clean it up. If you know what to look for sometimes they show, a clutch part may out a little by looking at the space between them on the carb.

 

Sometimes it can't be seen.

 

Is the drum also ok?

[champagnecharly]

Sorry I dont understand what you mean by:

 

"a clutch part may out a little by looking at the space between them on the carb. "

 

Space between carb & clutch?

 

drum "looks" ok

[s.varty]

That will be a broken clutch spring allowing the clutch to engage at a low speed.

 

I,d agree with that:thumbup1: