View Full Version : Stihl FS55R String Trimmer Clutch removal?

07-31-2011, 01:18 PM
Hey mechanics, I need a dash of help.

I have a Stihl FS55R string trimmer that I won at a landscaping show a couple years ago and hardly ever used it until rescently. It just never compared to the larger echos I have. That's another story.

This trimmer has been nothing but trouble from the beginning. Rough running, vibration and hard starting. I am using the proper fuel, exhaust screen is clear.

After sitting for 2 years I decided to use it around the house here, has about 12 -15 hours light use at best and has been harder and harder to start. I have put a carb kit in it for fun and replaced the spark plug then when it wouldn't start at all I realized I was getting no spark so dropped in a new ignition coil and properly gapped it. Replaced the switch as well just in case. Still no fire so my only other idea is that the flywheel key is sheared.

I can not for the life of me figure how to get this clutch assembly off, is there a hex or torq bolt down inside the shaft and what size is it if there is one.

Thanks in advance for any help you folks can offer!

07-31-2011, 01:25 PM
Most of the Stihl fasteners are T27 Torx. I don't have a breakdown on the FS55 so it's a stab in the dark for me, but that would be my inclination.

07-31-2011, 04:07 PM
How did you set the gap for the coil, although the rough running / vibration and hard starting would indicate
to me that the clutch is sticking but if you're not getting any spark I would assume the trouble lies with the coil
and the gap between the coil and the flywheel magnetos, it is very unlikely that the flywheel or its magnetos
have gone bad.

Then it might be the only problem is that your clutch is sticking (or stuck) to the plate that engages the shaft,
once they're always engaged to where the clutch no longer disengages you will have the rough runs and the vibration
and the hard starts, however you should still be able to start it some kind of way and so long you run it Wide open
it should do that without any sort of hassle, that having been said you may have to replace the clutch itself but without
looking at it I'm taking some of my best shots in the dark.

07-31-2011, 04:37 PM
Thanks for the replies,

To set the proper gap for the new ignition module I used STIHL Part # 4118 890 6401, its a gap tool that sets to the eight thousands of an inch. " The shop I bought the coil from let me borrow it. However they don't want to tell me how to get that clutch off, they want me to bring it in. At $65 an hour I am pretty sure i can get it off one way or another. If I knew the proper technique to do so would be easier than what I had in mind.

07-31-2011, 07:34 PM
T-27 screw in the clutch hub, right hand thread. Then ya gotta unscrew the clutch shoe assy., then pop off the flywheel.
The flywheel has a molded in key, so if its sheared, ya need to get a new flywheel.
Even with a sheared key, you should still get a good spark, just not at the proper time.
Are the magnets OK ? If they look blueish they're shot.

07-31-2011, 08:24 PM
BIGFISH. Thanks a million. You answered my question exactly as I needed.

The magnets in fact were blue, they had a very slight rusty look and like an aqua blue hue. I took 3200 grit sanding cloth and polished them up to no avail.

I will pull the flywheel and replace and hope it works fine. I really don't like this trimmer but I really dislike being beaten more ;)

What causes these magnets to turn blue?

Thanks again for every ones comments and help.

07-31-2011, 09:13 PM
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