DeckSetter
ArboristSite Operative
Wasn't there a post recently about someone getting stihl oil with not enough oil in the bottles? Could it be too little oil in the mix? What color is your gas?
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Just throwing it out there for discussion...
SteveSr
Addicted to ArboristSite
BINGO! The saw was run too lean! The "legal" RPMs that you got was due to the limited coil and NOT the carb "H" setting.
Limiters only have a maximum RANGE of 3/4 of a turn so most times there is a certain pre-adjustment that is added to the screw BEFORE the limiter cap is installed. So with an unlimited 1 1/8 turn out you were already 3/8 of a turn too lean on a stock saw. Then you modded the muffler which made it even leaner causing the near seizure.
Homelitexl903
CAD...The struggle is real.
You obviously haven't seen many huskies then.
Just kidding, the last time someone worked on my truck I ended having to snug up everything myself, it was almost as if they were not even trying.
D
Deleted member 135597
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Again, I'm not denying that I caused it, but it was scored BEFORE the dual port muffler cover which stihl sells OEM. I saw the scoring when I was installing the cover.
jmssaws
Addicted to ArboristSite
It's not straight gassed but not enough oil or it was separated from the gas a little.
Ran longer it could have got all 4 corners
There's nothing wrong with the saw so what else would score it on the intake side? Lean would get it on the exhaust side.
Ran longer it could have got all 4 corners
There's nothing wrong with the saw so what else would score it on the intake side? Lean would get it on the exhaust side.
D
Deleted member 135597
Guest
The cylinder was scored by the second time i ran the saw, if not before. I dropped a 75 foot oak and bucked that all up with the same gas mixture AFTER the cylinder was scored.
D
Deleted member 135597
Guest
I'm going to install an unlimited coil and tach check what my 1 1/8 to 1 1/4 setting with 100ll fuel is. What rpm you think will lean seize a saw? I doubt I'm even close to 14k
Big_Wood
westcoast dweller
i tell ya, guys are so ****'n dead set on throwing out the AS classic answers. "it's lean", it"s got an air leak. **** what a joke. a limiter is just that, it's only purpose is the limit the RPM. so why do they need a limiter? efficient tuning ALWAYS ends up above the limiter otherwise they wouldn't need one. anybody who has swapped an unlimited coil on a 461 and tested the limits know they will happily run at 14.5k stock. i never pushed it to 15 but i bet it would happily run at that too. again, the first one i ported tached to 17k. i tuned it back to 15.5 so it wouldn't disintegrate as a work saw. would 4 stroke in the cut occasionally so put it up to 16. still felt rich so put it at 16.4 and it ran that way happily without a hickup for 175-180 tanks before i got sick of the saw itself. ran on company mixed 87 octane 50:1. i'm sure it was likely the cheapest fuel and cheapest oil the company could get their hands on too. an absolute powerhouse that will slaughter any 372 work saw but has all the same ****** things about every other stihl.
D
Deleted member 135597
Guest
Exhaust side of piston. Still think it was run too lean?
D
Deleted member 135597
Guest
Does this decompression valve look like it was stuck open at one time? That looks like a lot of staining around the bleed port for a saw with only a few tanks of fuel through it.
D
Deleted member 135597
Guest
This is where the bleed port was facing against the cylinder. Like hot gasses were blasting through the bleed hole
This...
Khntr85
Addicted to ArboristSite
I can agree, I will say this I believe my 461 can be tuned alittle far with factory settings... which I believe helps save the companies ass from guys that just buy the saw and never touch the settings....I have never ran a ported 461 though...
SteveSr
Addicted to ArboristSite
Call it lean, call it hot... whatever. The bottom line is that the piston got too hot and expanded to remove all of the oil clearance and begin to seize. There may have been other complicating factors as well such as:
1. As mentioned previously the ring gap may have gone to zero creating debris or a high spot.
2. The saw was brand new and not broken in so the saw was already tight and didn't take much overheating to start a seizure.
As for the location of the seizure it is usually on the hottest part of the piston (most thermal expansion) which is on the exhaust port side. However on a new unbroken-in saw the rules may change to favor the tightest part of the cylinder as where the seizure begins. In this case it appears to be on the "4-corners".
So yes, I still think it was lean. If this saw was well broken-in I doubt that the carb setting was lean enough to cause this kind of damage as the clearances would likely have opened up enough to prevent the seizure.
Homelitexl903
CAD...The struggle is real.
This saw needs to be on the X-files. What if some unidentified object made it's way in during assembly. Possibly a sloppy or hungover worker or just random crappy accident that happened to end up in this mans hands? Good luck on rebuilding and sorry about your luck.
Full Chisel
Slingin' Stihls and runnin' Huskies
That saw was clearly not run lean. The scoring is highly localized and on the intake side. Could be piston or ring tolerances out of spec...Stihls are known to have tight tolerances from what I hear on the interwebs.
I don't understand why the OP would spend big bucks at a dealer on a new saw and not take it back when something goes wrong with it under warranty. That damage is likely Stihl's fault. Not every single unit that comes from the factory is going to be 100% perfect...there are going to be a few turds in the sandbox.
I don't understand why the OP would spend big bucks at a dealer on a new saw and not take it back when something goes wrong with it under warranty. That damage is likely Stihl's fault. Not every single unit that comes from the factory is going to be 100% perfect...there are going to be a few turds in the sandbox.
Karla
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Woody,
Based on your decompression valve picture, with the exhaust, I would say the decompression valve did not close at some point. It should have closed during the compression stroke of the engine and before the plug fired, and definitely before the piston was in the exhaust stroke. Also most decompression valves will close at about 30 PSIG, so just a slight pull is enough to close the decompression valve (note: Not sure about Stihl decompression valves but I have tested alot of Husqvarna decompression valves), the saw doesn't even have to fire. However I have seen some decompression valves that take 100 psig to close. So here is the question, If the saw was brand new and had 150 psig of compression, then the decompression valve should have closed, but once the piston was scored and the compression was much lower did the decompression valve work ? (Sort of the chicken or the egg syndrome). You can test the decompression valve to see where it is at right now.
Based on your decompression valve picture, with the exhaust, I would say the decompression valve did not close at some point. It should have closed during the compression stroke of the engine and before the plug fired, and definitely before the piston was in the exhaust stroke. Also most decompression valves will close at about 30 PSIG, so just a slight pull is enough to close the decompression valve (note: Not sure about Stihl decompression valves but I have tested alot of Husqvarna decompression valves), the saw doesn't even have to fire. However I have seen some decompression valves that take 100 psig to close. So here is the question, If the saw was brand new and had 150 psig of compression, then the decompression valve should have closed, but once the piston was scored and the compression was much lower did the decompression valve work ? (Sort of the chicken or the egg syndrome). You can test the decompression valve to see where it is at right now.
Full Chisel
Slingin' Stihls and runnin' Huskies
That decomp did look suspect. But there again, a leaky decomp creating an air leak should show the most scoring on the exhaust side, no?
