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dave02 - thank you, turned out the internals on the carburetor were fine, the saw has gone back to the owner.

Local guy stopped in yesterday morning with a quite new Stihl MS250? (I didn't take any photos...) said it wouldn't start. Normally on a Stihl they are flooded so go through that routine...nothing. Check the fuel level, full, but very purple in color, asked where he gets the mix oil (I knew he'd bought a 4 oz mix and a gallon of Poulan Pro bar oil from me last month), said the boss bought it. Remove the air filter to access the spark plug, very thick layer of "fuel mix" in the carburetor, plug is wet but doesn't smell like gasoline. I asked about the time line for his issue...before of after he bought the gallon of PP bar oil... just after he bought the PP bar oil and the "young kids" had used the saw & put it away without saying anything...

Dumped out the fuel tank filled with very thick/dark purple "fuel" and poured in a little fresh mix, shake it around and dump it, add some fresh fuel and after a couple of primes to clear the carburetor the saw was running (and smoking) until the bar oil was cleared out of the fuel system.

Mark
 
Could be interesting in the AM.
MS271, backfires when starting and no run
So far, customer has installed AM carburetor and ignition module. No diagnosis, just parts cannon.
And no original parts.
Flywheel key and piston condition first, then a visual inspection.
Good thing I like a challenge. And have used parts.
 
So- the rest of the story on the MS271.
Tried to start, backfired.
Check flywheel key- looks like new (as does the saw).
Called customer- asked for original parts. Delivered to shop. Asked why they were replaced. Said no spark.
Removed AM coil. Install original. Has spark. Started in 3 pulls.
Would not accelerate. Could not adjust AM carburetor.
Installed original carburetor. Started 2 pulls. Idled, accelerated, just enough rich on top end.
Runs like new.
My opinion of aftermarket parts has been reinforced.
 
I here ya about aftermarket parts. Been trying to clue my nephew in on chinesium parts. He replaced all his coils on a Chevy a while back, tossed the originals, and had a dead hole a week later.
No comparison in metallurgy, plastic quality, and fit with Stihl vs.knock offs. I put a cheap top end on my same nephews 064 a couple months back. The piston made it about 3 or 4 days before it exploded. Better off to buy once, and cry once.
 
So- the rest of the story on the MS271.
Tried to start, backfired.
Check flywheel key- looks like new (as does the saw).
Called customer- asked for original parts. Delivered to shop. Asked why they were replaced. Said no spark.
Removed AM coil. Install original. Has spark. Started in 3 pulls.
Would not accelerate. Could not adjust AM carburetor.
Installed original carburetor. Started 2 pulls. Idled, accelerated, just enough rich on top end.
Runs like new.
My opinion of aftermarket parts has been reinforced.
To try to figure that stuff out over the internet with half the parts being China junk is an effort in futility. I stay away from that junk always.
 
To try to figure that stuff out over the internet with half the parts being China junk is an effort in futility. I stay away from that junk always.
In the case of these ms170s I'm finding most everything is China made.
I picked up 10 that were used as props in a haunted world near me. $20ea. No chains so run at WOT with no load and 50:1 mix. Gee, what could go wrong? 🤣
I might get 5 working saws with just replacing rings. Sell for $100 around here :p
The rest will be ebay parts.
I plan on cheap aftermarket pts for whatever I might need ...probably come from the same factory 🙄
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Pick up two parts 044 saws to hopefully build one saw in the future. Saw 1 needs a hone and probably seals but it just a chassis, so not much to check. Saw 2 has a burnt piston and some scoring on the cylinder. Not sure if it will clean up or not, but I can hardly feel it so we will see. Both are slant fin 12mm Mahle cylinders but the burnt saw has a lot of signs that the saw was running hot for extended periods of time. Also got a new style 044 tank but it’s got a cracked front mount so I’ll try a plastic welder and see what I can do. Looking for a recoil, flag, and clutch cover so if any of you all have that I’ll be interested. IMG_5639.jpegIMG_5635.jpegIMG_5636.jpegIMG_5641.jpegIMG_5640.jpeg
 
Tried to clean up the burnt cylinder with a gentle wet sand but it doesn’t look promising. The remaining marks are barely there but I think they might be through the plating right below the exhaust. Maybe someone can chime in as it’s not the worst I’ve dealt with but won’t come clean.
 

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Tried to clean up the burnt cylinder with a gentle wet sand but it doesn’t look promising. The remaining marks are barely there but I think they might be through the plating right below the exhaust. Maybe someone can chime in as it’s not the worst I’ve dealt with but won’t come clean.
Have you tried Muriatic acid to pull any residual aluminum?
 
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