550XP Auto Tune Diagnostic Reults

I have a 550XP I bought new about a year ago and it’s by far the best saw I own pound for pound.
I got this guy and two others, a 235 and a 450, on CL deal.
Compression on this one was next to nihl! But from outside it looked pretty good.
So I brought it to a local shop that has ( hard to find one equipped) the auto tune diagnostic tool, hand written record above.
Two questions;
1) what would you do in light of the diagnosis
And
2) what should an Auto Tune diagnosis cost?

 

I'd start by pulling the muffler and see if the pistion is scored. Do a leak test. As for cost on a diagnostic print out price mine was $30.

 

I'd do a pressure/vac test. If it doesn't hold pressure I get out my trusty soapy water spray bottle.

 

Yeah, I thought that would be the number. This shop, pretty sure, just eyeballed it. They just sent the tech to school the week before. I paid more than 30. No print out, but a hand written record because they’re not set up for it yet.
And I’ll pull the muffler for sure, but I’m pulling the cylinder to see what’s going on. This thing has compression like it has no piston ring.

 

x2 keep us posted! M2theB

 

Nice score. This will be I teresti g to see how it pans out. Good luck!

 

Thanks. I got all three of those saws for the same price as the diagnostic.

I think I’m going to fill it with non ethanol fuel and flush it via crank and primer, dump and flush again, replace the plastic and p/c.

Watching and reading on the tools to leak check this puppy and the evidence leaning toward bad fuel, and it smells bad in the tank and it only has 22 hours on it, I think it’s a reasonable approach. Standby for more.

 

It’s not good, but what was expected.
What I didn’t expect was a missing circlip on the starter side.
I’m thinking that came out and started the downfall of this one

 

Aside from the obvious insult, the saw is pretty clean.
But something is bothering me about it.
It still smells a little. And the 450 part saw that came with it stank. Like cat pizz or something.
There’s a story behind the three saws that the previous owner wasn’t sharing.
Anyway, OEM p/c kit is on the bench and fuel and purge lines were ordered today from local shop.

 

scoring all the way around piston is straight gas

 

Intake side.
What do think with this info?

 

when completely around scoring it is straight gas that caused the failure
if it was on just one side it would be lean seized but with these new mtronic auto tune saws kinda hard to do that

 

I’m gonna play the odds.
Going back to the diagnosis.
Tank smelled bad, so bad gas. And damage to the p/c ( there’s a liberated circlip).
Not much run time so seals aren’t likely.

I hope it’s a good bet.

 

Maybe original owner was too embarrassed to say he straight gassed it?

 

Sounds plausible. Good call dall

 

First tank straight gas saw I picked up

 

Looks like there was a path across the bottom of the cylinder and top of the gasket for air to pass. Follow the schmootz all the way across the surface.
And looking harder under the muffler, the greasy dust layer is pretty defined.

 

What’s interesting is there is no hold down bolts in that area.
Only the muffler outboard of that area would try to help hold that down.
And very interesting is that this saw had a missing muffler hold down bolt.
Hmmmmm!

 

I'm not following about the potential for an air leak. Are you implying the bottom of the cylinder is not flat? Have a straight edge to show this?