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Husqvarna 576xp - FixerUpper

hacskaroly

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There have been multiple threads of saw builds/rebuilds/upgrades that I have learned from on this forum! I have a project saw that I am taking on, so I figured that I would share whats going on with it. This is a Husqvarna 576xp that I found pretty much as you see below. I had to scrounge through a box of parts to find the carb, cylinder, top-cover and clutch cover. This saw had an unfortunate accident when the top piston ring appears to have shattered, gouging the piston and scoring the cylinder. At that point, the user decided it was trash and tossed it into a pile of parts saws (a pile that I have already pulled two 372s out of and put them back into service with a little elbow grease).
576 Left Side.jpg
The piston with chunks of the top ring embedded into it (exhaust side).
Piston Chunk 1.jpg
Side view with chunks removed -lower ring broke as I pulled it out.
IMG_20240102_173641.jpg
A view from the top with the chunks out...
Piston Chunk 3.jpg
And finally the cylinder - I am wondering if a little sanding and Scotchbrite cloth will clean it up???
576 Cylinder Score 1.jpg

Unfortunately I am at the mercy of work to buy the parts for this, but I have seen on Traverse Creek/Saw Salvage website a piston kit and a piston and cylinder kit which are both really reasonable and I have heard nothing but good so far about the equipment purchased from Duke's. I am hoping they will go for one or the other. If I thought the piston was salvageable, I would have sprung for new rings and given it a try, but after digging out the fragments, I don't think its fixable.
 

beaglebriar

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I built one of these recently. They’re extremely smooth cutting saws. It’s really difficult to tell for sure but I think that cylinder might be too far gone. Is that scoring through the plating?
 

hacskaroly

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I was working on cleaning up the carb last night, I will post more pictures when I am finished with it, but wanted to post one first. While dissembling the pump side, I found an extra "diaphragm", a clear plastic piece along with the standard reed diaphragm and the gasket. The plastic is quite stiff, I wonder is it supposed to help support the diaphragm? I did a quick look up on repair kits for the carb (Zama C1M) and none showed the clear plastic piece. I think I have a couple of other 576 carbs in a parts box I will take a part and see if they have it too. Have any of you run across this piece in your carbs or repair kits?

576 Carb.jpg
 

Duce

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hacskaroly

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hacskaroly

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Nevertheless....keep that in mind....regarding diapfragm materials....
I have seen that video (good info) and have seen kits that come with the different material diaphragms. This one though is odd as the clear plastic piece does not have any flaps or reed valves that the black one does. I thought that someone might have screwed up and put two diaphragms in it together, but the clear one mostly covers the black one, but not fully. I am wondering if the clear one is a support for the black one. I have not worked with many Zama carbs, so wasn't sure if it is more of a Zama thing as I have not seen this with any Walbro or Tillitson carbs I have worked on,
 

Tomos770

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the clear one mostly covers the black one, but not fully. I am wondering if the clear one is a support for the black one. I have not worked with many Zama carbs, so wasn't sure if it is more of a Zama thing as I have not seen this with any Walbro or Tillitson carbs I have worked on,

I see it the similar way (if clear one was there from factory)....not as a support....but to add more "volume" for a fuel...as a spacer!

Diaphragm can pump more fuel if you elevate it slightly.....?

How were they put together ?
 

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beaglebriar

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I was working on cleaning up the carb last night, I will post more pictures when I am finished with it, but wanted to post one first. While dissembling the pump side, I found an extra "diaphragm", a clear plastic piece along with the standard reed diaphragm and the gasket. The plastic is quite stiff, I wonder is it supposed to help support the diaphragm? I did a quick look up on repair kits for the carb (Zama C1M) and none showed the clear plastic piece. I think I have a couple of other 576 carbs in a parts box I will take a part and see if they have it too. Have any of you run across this piece in your carbs or repair kits?

View attachment 403001
I’m not exactly certain what the idea is behind that clear piece but I’d reinstall it. It certainly won’t hinder performance.
 

legdelimber

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I think that the clear sheet has two "flaps". Look at the cut out lines that define them.
Looks like it fits against the cover and the flaps match to those two chambers in the cover.
That's a complex die (extra work and maintainence) to cut those shapes with the narrow cuts, without a good reason.

But where does the flow pass to?
Doesn't look to have a good solid surface to work against though. Except against the pump dia which is against the carb body.
I'm guessing these may be a way to shape or "tune" the impulse or flow/movement through the area?
 

hacskaroly

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I took apart another carb I had in a spare parts box to make sure I had the right order on the diaphragm pieces, they go in this order:
1. Carb body
2. Black diaphragm
3. Clear plastic sheet/diaphragm
4. Gasket
5. Carb cover

576 Zama C1M Carb.jpg
Closer Look...
576 Zama C1M Carb Close.jpg
What it looks like with the black diaphragm on the carb body and the plastic diaphragm on the black diaphragm. On top of this would go the gasket then the cover.
576 Carb Diaphragm Layers.jpg
Since it came this way, I put it back together this way, but this is the first time in all my many (two) years working on chainsaws that I have seen the additional plastic layer in the carb.

Also, I had to compare the bottom of the cylinders to see the difference between the e-Bay listed "576" cylinder and the one I have, now I can see the difference.
My 576 cylinder is on the right.

Untitled.png
 
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