Ran ms461 on straight gas

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Gu_42

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I ran my 461 on straight gas without realising, it got pretty hot abd was seized when I pulled it after it stalled.

Its turning over now its cooled but doesn't have much compression.

Im guessing the piston and cylinder are stuffed? Is there anything else that might be gone?

Is it worth putting an oem piston / cylinder in? Or should I go aftermarket?
 
Welcome to AS Gu, sorry it's under these circumstances, but it's how many of us found this place :cheers:.
How long did you run it for.
Have you pulled the muffler cover and inspected the piston, that's where I would start. The piston will be junk, the cylinder may or may not be. Inspecting the piston can give an idea of how bad it is. If you can get some pictures we can make a long distance diagnosis/guess of sorts, but you won't know for sure until you remove the cylinder and get it cleaned up.
I personally don't use any AM cylinders unless they are Italian made.
 
It didn't run for that long maybe idled for 5 minutes then a couple of cuts. I remember thinking it felt hot when it stalled, I didnt realise realise it was running without oil and thought it was out of tune.

I tried to tune it for a couple of minutes, it stalled again thats when I tryed to restart it and it was seized for a moment. Took it to the shop after that and they pulled the muffler off and the piston was scored. There pulling it down this week to see what damage has been done
 
Cylinder should be savable is my guess.
Did the shop say that the cylinder may be savable? I've never heard of the shops saying they would save a cylinder, it's not profitable in their eyes, maybe yours are different.
 
He said he may be able to save it, and he would just do the piston if possible.

Is it possible anything else was damaged due to getting hot? The saw is only 2 years old and hasnt been used a whole lot....
 
He said he may be able to save it, and he would just do the piston if possible.

Is it possible anything else was damaged due to getting hot? The saw is only 2 years old and hasnt been used a whole lot....
That would be great. If they say it needs a cylinder tell them you want the old one, don't let them throw it out, insist you get all the old parts back.
That should be it.
 
So is it worth paying double the price of the aftermarket piston and cylinder to get a genuine piston and cylinder?

Just it case it comes to that, I want to know what to tell them to put in it...
 
So is it worth paying double the price of the aftermarket piston and cylinder to get a genuine piston and cylinder?

Just it case it comes to that, I want to know what to tell them to put in it...
I already stated my opinion on that. If your going to straight gas it again you may want to though lol.
There are few repair shops here that will use them, if there a dealer(stihl in this case) they get paid to use genuine parts and that's what they would want to give a warranty, not an AM part.
 
I got my saw back, they hadn't touched it so I decided I'd pull it down my self. I've uploaded some pics let me know it you think the bore is stuffed
 

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The piston is obviously shot, the cylinder may clean up(hard to see it on my phone), but you won't know until you try.
Have you watched any videos or read about cleaning it up.
Id be more inclined to sand it rather than using muriatic acid.
Id post a link, but cant right now.
 
I bought an MS461 not long ago after it had been straight gassed. I thought the cylinder was going to need replaced as it looked pretty bad, but I was able to clean it up. I also replaced the piston with a Meteor which came with Caber rings, and it has been running great so far. I think the piston and rings cost around $38. The cylinder I cleaned up with acid and did some light honing afterwards and looked good as new.
 
I bought an MS461 not long ago after it had been straight gassed. I thought the cylinder was going to need replaced as it looked pretty bad, but I was able to clean it up. I also replaced the piston with a Meteor which came with Caber rings, and it has been running great so far. I think the piston and rings cost around $38. The cylinder I cleaned up with acid and did some light honing afterwards and looked good as new.
I think I saw the pics of that one finished.
Great saws, plenty of torque.

The reason I don't suggest using the acid is that if there is small spot of plating missing then the acid can get under the plating and damage it. Small imperfections that won't snag a ring aren't a deal breaker depending on the location in the cylinder.
 
The piston is obviously shot, the cylinder may clean up(hard to see it on my phone), but you won't know until you try.
Have you watched any videos or read about cleaning it up.
Id be more inclined to sand it rather than using muriatic acid.
Id post a link, but cant right now.

I just did a search, I'm going to try sanding it with 400 grit sand paper and see what happens
 
I just did a search, I'm going to try sanding it with 400 grit sand paper and see what happens
I dont blame you. They are too nice to risk. When I started on it, I was fully prepared to buy a new cylinder so I didnt have much to lose. The acid helped for sure, but the hone did the best job. I sanded for a long time before honing, but some stubborn parts I could not get off. The hone finished like it was fresh out of the machine shop.
 
Ive sanded it a bit, im not sure how much of whats left is aluminium and how much is scratches in the bore.

And there seems to be a nick of the coating up the top of the bore you can see in one of the pictures.

Am I wasting my time?
 

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Ive sanded it a bit, im not sure how much of whats left is aluminium and how much is scratches in the bore.

And there seems to be a nick of the coating up the top of the bore you can see in one of the pictures.

Am I wasting my time?
Does any of it catch your nail? It's hard to tell from pictures exactly, but I wonder how much a hone would help. That spot above the port would worry me though. If that is actually a hole or chip, then it may not be worth your time to keep trying to remove scratches.
 
Good luck with the project. Out of curiosity how did you manage to use straight gas in the saw ?? I use a one gallon gas container with chainsaw labels all over it... and i put oil in it before i even add the gas. I dont run a lot of saws... so maybe the 2 cycle deal for me is rare enough to keep my attention... i had a bunch of 40 hp boat outboards.. and those got the oil put in before i added gas as well.
 
I had no oil to mix it after I filled the fuel can up, so I wrote on the can in a paint pen "not mixed".

2 months later I picked up the fuel can and the paint was gone, so I assumed I'd mixed it.

The paint must have come off due to some fuel residue, so that combined with my bad memory is how I ran straight gas in it!
 

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