Is running a scored saw okay if its getting the job done?

[NewToStihl]

I'm sure this information is available somewhere in the bowels of the forum, but these key words bring up an overwhelming number of threads...

So, here it is. I have a saw that I bought with a scored piston & cylinder. I'm fairly certain it was scored from a lean condition caused by cutting with the "H" screw turned out about half as much as factory recommended. For the sake of my curiosity, let's assume that was the cause and not some other issue related to the air/fuel delivery. Despite the piston & cylinder damage the saw still makes enough compression to idle, run, and cut well. Not high compression by any stretch, but enough to keep it running. Frankly, to the untrained eye (me, for instance!) it seems to work just as it should and had I never looked into it I wouldn't have any idea it's damaged.

Since it seems to work well enough for my needs at the moment is there any reason to avoid using it? With a good tuning and appropriate fuel mix is it possible to cause additional damage outside of what already needs replacing (cylinder, piston, rings, etc.)? Would I be a moron to go ahead and continue using it? My assumption is that the scoring may/will get worse between the cylinder & piston, but is other damage possible?

Thanks.

 

[ZeroJunk]

Just run it. The vast majority never know the piston is scored until the rings seize and it quits. Won't be anything new.

 

[NewToStihl]

Just run it. The vast majority never know the piston is scored until the rings seize and it quits. Won't be anything new.

Thank you. If you don't mind, I have a follow-up question. If the saw has no other problems (was just run lean due to operator error), is now tuned correctly, and only gets a good quality fuel mix will it eventually continue the damage and quite running or seize up, or is there a chance it'll run 'forever' if treated well from here on out?

 

[dl5205]

"I have a saw."

My 1st thought is "Run it like you Own it".

But that thought is tempered with a query. Is it a clapped-out ms250, or a near-mint 242xp? A haggard 55 or a like-new 5000+?

If it's an average condition, average-worth kinda saw, and you're keeping it for your own use, Just Smile and Cut. But if I were gonna flip it, it'd get at least a good cleanup (cyl. and piston) and a new ring, and be sold only with full disclosure. But that's just me.

 

[fearofpavement]

Thank you. If you don't mind, I have a follow-up question. If the saw has no other problems (was just run lean due to operator error), is now tuned correctly, and only gets a good quality fuel mix will it eventually continue the damage and quite running or seize up, or is there a chance it'll run 'forever' if treated well from here on out?

Probably.

If the saw is a throw away cheapo, I would continue to use it as is. If the saw is worth anything, it may be worth putting a new piston in it. Usually, but not always, the cylinder can be cleaned up with acid and just a piston and rings will put it back in shape.

What model is it? That could matter.

 

[splitpost]

quit using it before it really does damage

 

[dl5205]

quit using it before it really does damage

If you're unsure, this is the best advice.

I have a 12 year old 372xp that I bought new. Babied all it's life. Back in the fall, it had a coupla "hinky" moments. Over-ran a little once, wanted to lean out in the cut another time. I drained the fuel out of it, and sat it aside 'till I get time to properly and totally check it out. May just be fuel line/filter, but I'm not chancing it.

 

[NewToStihl]

There IS a difference between lying and witholding information, right???

I have really good condition Stihl 090 that I bought scored. I eventually plan to rebuild the top end and sell it, but I want to do some cutting with it first. I have a new piston & cylinder on order, but I can barely resist the urge to use it as-is. I would prefer to do some cutting with it now and sell it with a freshly rebuilt top end so that the new owner can execute the break-in as they prefer. I'm reasonably new at this game, but I know there are some very different theories on new engine break-in. I'm even considering selling the saw as-is with the new-in-box pistion & cylinder after it arrives.

The point is, I want to run the saw as I received it, but don't want to screw it up more than the previous owner did.

For the record, the current cylinder cannot be spared as some of the coating us gone just above the exhaust port.

 

[dl5205]

"The Truth, the Whole Truth..."

 

[dl5205]

quit using it before it really does damage

 

[fearofpavement]

If it was me.... I would pull the cylinder, clean up what I could, smooth the piston as good as I could and then reassemble it and cut wood. since you already have parts on order, you aren't risking that much.

For "new to Stihl" you started out big!

 

[ZeroJunk]

Yep, if you keep using it the saw will explode and kill you and any bystanders.

 

[blsnelling]

You may currently be able to clean up the cylinder and install a new piston. Continue to run it, and you're just doing more damage. If nothing else, clean it up and put it back together. Just don't continue to run it the way it is.

 

[dl5205]

Yep, if you keep using it the saw will explode and kill you and any bystanders.

'Dead bystanders' made me think of 'Red Suspenders'. IDKW

 

[NewToStihl]

Okay . . . shame on me for wanting to ride a wounded horse.... I get nervous around new (expensive) parts!

That said, I'm trying to learn as much about saws as I can, so I gotta ask; what additional problems would arise from a situation like this? Not just asking about this particular saw, but in general.

Heat from the scoring/seizing process ruining adjacent components? What else?

 

[dl5205]

On a good day, it'd just lock up. On a real bad day, chunkies may get in the bottom end and Raise Cain.

 

[NewToStihl]

If it was me.... I would pull the cylinder, clean up what I could, smooth the piston as good as I could and then reassemble it and cut wood. since you already have parts on order, you aren't risking that much.

For "new to Stihl" you started out big!

Yeah, don't get me wrong, I'm VERY new to this compared to the great folks I've seen here, but it occurred to me shortly after joining the forum that my user name had an unfortunate shelf life if I keep up with this hobby.....

 

[jjw]

I would think that as of right now your only looking at replacing the top end.
As the piston continues to go south it's loosing material (alum) from piston
and possibly ring material all getting stuffed into the bottom end and eventually
bearings then seals. All equates into more parts and labor, JMHO

 

[shawn022]

If the cylinder is OEM Mahle I would stop using it and pull the jug and see if it cleans up. Is the top end you have on order aftermarket? If you change out the top end the original cylinder would be worth something to some one, but worth way less if it needs replated.

 

[NewToStihl]

If the cylinder is OEM Mahle I would stop using it and pull the jug and see if it cleans up. Is the top end you have on order aftermarket? If you change out the top end the original cylinder would be worth something to some one, but worth way less if it needs replated.

The saw is currently all original as purchased so yes, the cylinder is OEM Mahle. I pulled it earlier this evening and there is no hope of clean-up; there is plating missing from a small section just above the exhaust port...

The top end I have on order is OEM. Very expensive, and drastically reduces my changes of getting my money back out of it, but this saw is in really good condition in my opinion and I just thought it would be a shame to put aftermarket parts on it...

I figure the old p&c will make a good conversation piece and/or paperweight for my desk at work!