660 rebuild

Peter

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I have picked up this saw as a potential rebuild project. It came back from the saw shop with the exhaust off and a big estimate for repair.

There is scoring on the exhaust side of the piston, but not on the intake side, as far as i can tell, and i think the inside of the cylinder head is clean too, although its kinda hard to get a pic of it.

What d'yall reckon?
 

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Cylinders are expensive. Try cleaning it up with oven cleaner to remove all the aluminum slag left behind from the piston and then see if the cylinder wall is scored through the nikasil coating. You may get lucky and only need a piston and rings.
 
A thought about screwed up pistons .Sometimes you can save them if they aren't too badly scored up.This one is past that stage unfortunately .

I just got in a Husky 281 that is just starting to show signs of pulling aluminum that I believe I can save .Usually they get too cooked before they get attention but luckily this I think did not .

When I tear it down I'll do a thread on the repairs .
 
660, 1200.00 saw new... Right?
Even if the the hole top end needs replaced ... OEM is what 300.00 or there abouts? I think it would be worth doing as long as the crank case is sound.
 
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  • #9
Heres how the cylinder cleaned up.
 

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Not perfect but not too bad either (although I'm no expert). Hopefully it will hold good compression with a new piston and rings. :)
 
I'd try and hone it out just a bit more Peter, it's not bad, but just a bit more and I think most of the lines in the second pic will come out.
I would certainly not be afraid to run it, nice work!
 
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Right, I was a bit wary of over doing the honing, but if it can take a bit more then it will get some more.

Thanks everyone for your help so far.
 
Get some fine grit paper like 600 and use kerosine. plenty of it .Clean all around the chamfers on the ports to make sure all that tramp aluminum is removed . It looks like some residue on the bottom of the intake .As long as it's fairly smooth below the ports you should be okay . Above the ports you want it to be real smooth because that portion is where the rings seal and do their thing .
 
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Thanks Al, I'll do that in the morning. Anything I should watch out for when I reassemble it all?

Also, would you recommend more oil in the fuel mix to run the new piston and rings in?
 
Just oil the piston and cylinder good before you slip it back on .You don't have to mix a bunch of thick oil ratio fuel or anything .You might want to adjust the carb just a tad rich for a few tank fulls then lean it out and run it like you stole it .

Now when I said a little rich I didn't mean coughing away at 6,000 rpms blowing black smoke now ,just a tad bit .
 
If the piston doesn't slide in easily, don't force it, as a ring has possibly shifted in it's groove. Ask me how I know. :|:
 
If the piston doesn't slide in easily, don't force it, as a ring has possibly shifted in it's groove. Ask me how I know. :|:
Thanks for bringing that up,something I forgot to say .

Something I do that some may or may not do .Prior to final assembley on a cylinder that has been worked over I slide he piston minus the rings into it and move it up and down to check for obstructions if any . It might not be a back idea to do it with the rings on the piston for that matter .

If it hangs any place you can correct it before you snag a ring or otherwise cause damage .
 
That needs a hone out and oversized piston,Otherwise you WILL be doing it all again.

Sorry but its true.

Damian
 
Good trick if you could it .:roll:

Unfortunately most chainsaws have plated cylinders using a hard chrome or hard nickle lining .As such to rebore them to a larger size would entail both replating the cylinder plus obtaining an over sized piston of which for all intents is non existant unless a person goes to a specialy compnay like Wiseco and special orders one .

So while not being an impossibilty to do it would be very impractacle unless a person was so loaded full of money and time so they could figure a way to spend their money .

So Mr Ridgey with that said I think perhaps you need to investigate exactly how a saw is made prior to making suggestions on how to repair one as it appears you need more education on the subject .;)
 
Peter, I had the exact same thing with a friends 044, I cleaned the cylinder up and fitted a new piston and rings, it ran well with good compression, I hope the same happens to your saw.
 
As all mentioned, and I'd like to again emphasize, putting a chamfer around the inside port openings is very important. One lacking in a sufficient break on the edge, will chew up a ring very quickly. If the ring should break, it can be an expensive proposition to get the saw in good order again.
 
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  • #24
Well, shes back together and running. :)

Monday I'll set the carb up properly and cut some wood.

How many rpms should a 660 run at at full bore?
 
Forget the tach .Set it so it cackles or 4 strokes just slightly .When it gets maybe 1/4 the way or less though a 15" round it leans out when it needs the power .

After you run maybe a few tanks lean it some more until it gets maybe 2 inchs into the cut then leans out and powers up . After you've ran it some pull the plug .It should have a brown tint to it .If it's black you are too rich.If it's whitish you are too lean .Better too rich than lean .

Black plug-brown plug
 

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