UT20818 String Trimmer - How to get this piece off of the shaft

itsgalf

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I'm trying to fix up this UT20818 Homelite Zip Start String Trimmer for someone. I cleaned up the carburetor (had some gunk in the screen filter), put in a new spark plug (owner didn't know where the spark plug was) and tried to start it up. I wasn't getting any spark though (It has a good 120psi compression). I wanted to get at the ignition coil and see if anything was out of place, but I can't seem to get the red cover off.

When I disconnected the trimmer shaft, there's a covering (drum?) on the drive shaft shown in this picutre
IMG_20190828_161641615.jpg


So the covering is held on with a T20 screw. Got the cover off and there's this piece on it (clutch?).
IMG_20190828_161832110.jpg

Anyone have any experience with this? how do I get this off? Looks like it can thread off, but also looks like a pain to hold the shaft from turning without damaging. Probably a good time to get a good bench vice installed.


Also now that I'm writing this thread, I should also check to make sure it's not just a problem with the wires/stop switch before I mess with the ignition coil.

Thanks,
-Marco
 

bogdaN

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To stop piston from moving and shaft from turning---take spark plug out put some rope in the hole-pack that good to stop piston.Now remember on this 2-cycle spark kind-off weak.Good lock Marco.Dan
 

bertsmobile1

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It will be a left hand thread.
To remove the clutch you will need a bar with a hole in it big enough to go over the shaft near the middle of the bar
Then you will need 2 grade 9 bolts to act as drive pins, either side of the center hole so they bear against the strait section of the clutch.
After you make your special tool you then remove the spark plug and stuff as much rope into the cylinder as you can.
turn the clutch slowly to compress the rope then use the tool.
A sharp tap will work better than a hard push ( LH Thread remember )

The alternative is to use a BRASS drift and the BFH in place of your special tool but the clutch is easily damaged. doing that.
FWIW I use wrecked chain saw bars for these tools
 

itsgalf

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Thanks for the replies. Good information for removing the clutch. Forgot to reply to this thread.

I ended up returning the trimmer to the owner. Turns out it also had an issue where the cylinder would immediately flood after the first pull and after that I wouldn't be able to pull it over due to the flooding. The owner wanted to keep the costs very low so I told her I would I just return it instead of ordering a Zama carb rebuild kit and charging her too much for labor trying to figure it all out.
 

bertsmobile1

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Good call.
I get a lot of cheapie trimmers in for repair.
As you can see they are specifically made not the be repairable.
A new rope on one of them is $ 90 in labour ( 1.5 hours ) and a new trimmer is $ 70 to $ 110 so it is a no brainer.
Got a shed full of them.
When kids come around wanting old stuff to fix I give them an armfull

So the rule of thumb is starter in the front = throw away.

I find it really annoying that the authorities demand small engines run so lean to prevent tail pipe pollution that they have a very short working life.
Yet thay are happy to allow companies to make unrepairable products as if the only pollution that exists comes from the exhaust pipe.
If minimum quality ^ durability standards were followed we would be up to our necks in envionmential disasters , we would all be much better off financially & home owners would end up with all of the real labour saving devices in their sheds.
 

jp1961

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Hello,

The centrifugal clutch is right hand thread on this particular trimmer not left hand.

The clutch on a chainsaw would be left hand thread, because it's on the opposite side from the flywheel.

I've had success holding the flywheel with a oil filter strap wrench.

Securing bolts or nuts always tighten opposite the direction of rotation so a clockwise rotating assembly would require left hand threads. Counter clockwise, right hand threads.

I've used needle nose pliers then a crescent wrench (sort of a spanner wrench) to get these Homelite clutches off.

Burts right about the starter in front as they have 2 bearings only on one side of the piston, where the rear starter models have bearing on both sides of the piston.


Regards

Jeff
 
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