Stihl MS271 Farm Boss engine failure

[Tom M King]

Those are the only tools I loan out. I got tired of telling people I don't loan chainsaws or tools. I don't loan tools. We have mostly city folks with lake lots near us. There is almost zero chance that anyone could hurt themselves or anything else with one of these. They ran the last time I used them. I don't say that might have been over 30 years ago. I don't have time to work on them.

[Maurice Mcmurry]

Never borrow a gas can is another good rule.

[Adam Herman]

That looks like a classic case of gas only to me.

Attachment 514867

i have the same saw, and that was my first thought also.

[Maurice Mcmurry]

i have the same saw, and that was my first thought also.

Yup, It is always right at the port, where temperatures and friction are at their highest.

[Alex Zeller]

I had the same thing happen to my Dolmar. Ran great for almost an hour and then the power went. I could pull it over but it was hard. I ended up replacing the piston and cylinder. My saw was a $1000 saw so spending a couple hundred on it wasn't a hard decision. I was told that it's possible that the oil and gas started to separate and for the first half of the tank I burnt too much oil. As the tank got emptier and emptier the ration leaned out. I don't know if it was true but it didn't really matter.

I try to remind myself to shake up the saw before using it now. Often I'm not cutting near the house or if I am it's because I cut a number of trees down a couple of days earlier. So either the ride into the woods will mix it up or there's not enough time for the oil and fuel to separate. Had your saw been sitting for some time?

[Ole Anderson]

Jeremy, I see this is your first post to the Creek, welcome! Out of curiosity, have you posted this question on any arborist or chain saw forums? Wondering how you ended up here? BTW I have a MS 018 and a 290 Farm Boss that has served me well. It always helps if you complete your information so we see your location in the header.

Anybody else follow the Chicanic on YouTube? She repairs nearly a thousand small engines per year including a ton of chain saws. Here is a great episode about an MS 311. https://www.youtube.com/watch?v=XKcq...nnel=Chickanic

[Jim Becker]

I never realized there was a "smaller" version of the FarmBoss...mine is the 290 version, bought in 2000. It's been an amazingly reliable tool.

[Bill George]

I wonder if he was using Ethanol and got water in the gas then it would run lean with no oil?

[Alan Rutherford]

Jeremy, I see this is your first post to the Creek, welcome! Out of curiosity, have you posted this question on any arborist or chain saw forums? Wondering how you ended up here?...

I can't answer for Jeremy but there is no where else he could have found the depth of knowledge on almost any subject in the universe in a bunch of down-to-Earth people you find here. Pick any 10 or 20 topics in the Off Topic fourum and see what I mean.

[Edward Weber]

I never realized there was a "smaller" version of the FarmBoss...mine is the 290 version, bought in 2000. It's been an amazingly reliable tool.

Smaller is a bit unfair, it's really just an evolution.
All the Farm Boss models are in the 50cc range, similar weight, and roughly the same hp. It's really just a platform/engine change every so many years. The numbers fluctuate a bit but it's really just a trade off. A few tenths of hp loss for a smaller lighter engine is really all it's been.
Power to weight ratio is pretty much the same.

[Jim Becker]

Oh, I understand and agree about that Edward. I just didn't know about the alternative version with the .271 vs the .290

[Edward Weber]

Oh, I understand and agree about that Edward. I just didn't know about the alternative version with the .271 vs the .290

There will probably always be a Farm boss, it'll just be a little different every so many years.
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[Jim Becker]

Oooh...a widdle qkewtie one....

[Tom M King]

One other thing to consider before gambling on a cylinder kit would be to do a pressure test. A 2 stroke depends on keeping crankcase pressure up to a minimum level. If a saw is old enough for the crank seals to leak the least bit, the saw can get to the point that it's running lean, and can get lean enough that not enough fuel is getting to the cylinder walls which causes it to overheat.

To do the pressure test you hook a gauge that you can pump up in the spark plug hole and put plates over the intake and exhaust ports. You can slide the intake one in between the carb and the cylinder.

We haven't heard back from the OP, but if that saw ran lean, I would just replace it rather than spend money and time back into it.

If it has leaking seals, I understand they're harder to replace in a homeowner saw. Pro saws have cases that you can easily split for bottom end work.

Stihl used to have a third category called something like Farm and Ranch. The 290 was in that category. Those saws were build heavy expecting to spend their lives bouncing around in the back of a pickup. They had about the same power as the Homeowner line saws of the same size. I don't remember when they dropped that category.

The homeowner saws are mostly sold in places like hardware stores where they may or may not have someone that knows much about working on saws. The Pro saws are sold in shops where they have trained people that know what there is to know about keeping a saw running. Some shops may sell the whole line, and some may only sell the Pro saws who mostly deal with pro loggers. That's probably changed by now too though.

[Tom M King]

I did a google search for "pressure test ms271 youtube" and this is the first of many videos that showed up. I didn't watch any of them, so can't answer any question on a particular video.

https://www.youtube.com/watch?v=kZglEFo_HV0