My 576xp just quit. Looking for guidance

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Piston all damage at the exhaust port. The rest was clean.

 

Cylinder. It appears this is buildup, not grooved. If so is this something that can be repaired or should I get piston and cylinder?

 

I'd try removing aluminum first, then make the decision on ordering a piston and cylinder. Might be able to get away with piston, rings and whatever caused the burn down.

 

Since the aluminum buildup is below the exhaust port the only concern would be to get the high spots down to protect the rings/piston, correct? Not really going to loose compression below the port?

 

A split mandrel on a drill or dremel will work fine. My first experience removing transfer I use an exacto and emory cloth.


Before


After

 

Did what I could to remove the debris using the method in the previous post. Made real headway but the damage is just too much.


Everything is below the surface now. Ordered piston/cylinder. Want this done properly.

 

I'd say it'll be fine. You just need to get the rest of the transfer outta there. I had an issue with a real stubborn spot and the guy that did those videos instructed me to go further after I sent pics. Used a rougher grit right on the spot. The plating is a lot tougher than you'd think. Keep going!





BTW, don't throw that cylinder away...

 

What he said. ^^^^ . I have had older fun saw where the p/c looked almost that bad. Parts were more than I paid for the saw.... Cleaned everything up the best that I could put a new ring in and it runs fine.

 

I know you checked the bearings with the flywheel. It's apart check the wrist pin bearing ,double check the case bearings and crank bearing. You can just grab the piston take to TDS and push up and down without turning the crank.

 

I will keep working on the old cylinder to see if it cleans up better. I used 100 grit and 220 to get it where it is now. I don't think there is anything left on the surface and that all the remaining imperfections are scratches.

Couple pre-assembly questions:

Is a typical aerosol parts cleaner good for the crankcase? I did my best to reduce the possibility of debris dropping into the case but have to assume some made it.

Should I mess with the ports?

 

I use regular saw gas/oil mix to clean the case. Problem is, you may very well have a bearing seal leak which led to the meltdown. That doesn't appear to be a simple blame it on ethanol diagnosis. More guys will chime in here, but I've never had it cause something like you've pictured, nor have I seen anyone post something similar. Last thing you want is to throw parts at it only to have it do the same thing in a long cut. IMHO you need to pressure/vacuum test this saw. Use a piece of inner tube in between the muffler and cyl and between the carb and intake or cyl, then either use an impulse line or a plug adapter to apply the vac/press with a mightyvac or similar. Soapy water with pressure will find a leak you can't.

I removed the porcelain from an old plug and JB'd an adapter.

 

That's a question I think only you can answer. If you are confident, you can widen the exhaust a little (not beyond piston skirt). Without really good knowledge, I'd not touch transfer or intake ports. Just my .02.

 

I ordered an aftermarket piston too. Going to try my hand at porting the old cylinder and run that first. Just in case there is another problem that caused the failure, I can use the old cylinder as a guinea pig. Also going to make a trip to the nearest station that sells ethanol free fuel.

 

I personally wouldn't run that saw without checking for a leak. Bad fuel didn't do that...it leaned way out any you need to figure out why or you'll being replacing another toasted slug and jug sooner than you'd like. Even if you have to buy a kit and eat that cost it's still cheaper and easier than rebuilding the top end again.

 

Just curious do you leave your chain tensioned during storage- it can cause premature wear on crank casing seals.

 

Thanks basod I never thought about that, but it makes sense. I try not to have chains too tight, but will start to watch them when done using them.

 

Gonna hafta fill me in on this...how does chain tension cause seal wear during storage?

 

Chains get tensioned during install warms up stretches possibly readjusted due to slack and then it gets stored with warm/hot chain which contracts and strains the crank seals unevenly leading to seal failure.

 

If I recall I needed to tighten the chain when I began cutting, so I would say no excess torque in storage.