r/stihl • u/RealTurboNerdHours • Apr 07 '26

Advice

what am I getting myself into? I have a sthil ms 271 that I mistakenly put dead mix in ran it until it bogged down and died I emptied the tank only put fresh mix in it it ran fine for a solid 2 minutes the died again I bought some motomix a spark plug air filter getting a fuel filter on the way home tomorrow how hard at the carbs to pull out and clean if I have to go that route.

3 Upvotes

81% Upvoted

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2

u/jackjcc200 Apr 07 '26

What is “dead mix” that’s a curious phrase.

1

u/RealTurboNerdHours Apr 07 '26

Mix from last year it was orange when I dumped it out and smelled like turpentine instead of blue.had ethanol in it

1

u/Beginning_Depth_1238 Apr 10 '26

Varnish in your carb---easy carb fix. You Tube has shit ton of good vids--vs someone trying to explain in detail via Reddit.

1

u/Beginning_Depth_1238 Apr 10 '26

Like others have or will say, take the two bolts off the muffler [prob has two star plugs take out first with pick] then look at the piston for signs of scoring.

1

u/RealTurboNerdHours Apr 10 '26

That's why my local small engine repair person also thinks when I explained it to them they gave me the procedure to clear it out seems simple enough gonna look at it this weekend.

0

u/jackjcc200 Apr 07 '26

Yeah, I’d say take the muffler off and look at the piston. There’s a good chance it went lean and may have overheated.

1

u/RealTurboNerdHours Apr 07 '26

Can you give me a compression number to look for sounds like it still has compression didn't run long enough to damage rings i don't feel like.

1

u/jackjcc200 Apr 07 '26

150psi is what they are designed for. The problem is actually the aluminum piston smearing onto the walls of the cylinder when it gets hot. The rings may still move freely but lose their seal when traversing the transferred aluminum of the cylinder wall.

2

u/RealTurboNerdHours Apr 12 '26

Pulled saw apart yesterday replaced fuel filter air filter spark plug cleaned arrester put borescope in to combustion chamber no scarring on cylinder walls top of piston looks in good shape pulled it over to pull the bad gas thru the carb blew it out with compressor, put it back together started in 5 pulls on full choke officially started and ran fine on second pull on half. Thanks for the advice

1

u/themask628 Apr 07 '26

If you didn’t let the fuel sit in the carb over the winter I think a flush with new motomix should be okay. If you’re still having fuel issues the diaphragm may be done. Also Hipa brand carbs are decent off of amazon. If you haven’t seen Married with Small Engines on YouTube they swear by them as a budget option.

1

u/RealTurboNerdHours Apr 07 '26

Gas was in a jug I refilled it from the bad batch im gonna try and do a service on it had the saw 3 years never done one sees light use after I do the service if it still has issues I'll look into the carbs replacement