Cannot start MS260

[ZinTrees]

It ran fine when I put it away a year ago.

but it won't now, its ******, take the cylinder off and put a new piston, jug, and probably crank bearings in, then its got a chance of working again

no matter how much pulling you do, how much fuel you put in the cylinder or carb, no matter how much starting fluid you use, its never going to run again
without a whole new top end, I've dealt with my fair share of blown up saws and this is a textbook case of "she's toast"
I honestly would suggest buying a new saw, smaller saws like that aren't very expensive, for the average homeowner an MS250 is more than good enough, or for a few hundred more get a new MS261C, electronic carb so it will keep tuned right, pro saw with magnesium case, great power to weight, and hardly more expensive than the repairs needed for your saw

 

[user 188535]

Won't know anything more until he chimes in, if he does that is... When I read his 'starting fluid' comment I began to wonder. Starting fluid has it's place, just not with a 2 stroke. I actually winter store my bikes using Tru-Fuel with no oil in it. Saves me untold grief with gunked up carbs.

The straight (no added oil) Tru-Fuel states that right on the container. I don't believe you can buy Red Armor or Stihl canned fuel without oil in it, but then I'm not entirely sure on that. I just know you can with Tru-Fuel.

Like I've said before, I only use canned fuel in my saws because they don't get run often. Same with my Stihl FS66 brush trimmer. No added oil and no oil Tru-Fuel is easy to mix up if you don't read the label. I also use it in my outdoor power equipment that stays in the barn all winter so a gallon of it gets used in lots of engine fuel tanks. I've had more than my share of phase separated fuel in seasonal use equipment and it's always a job getting them to run in the spring with e-gas in the tanks.

Stihl sells it.

 

[lone wolf]

Ok ok ok, let me get my head around the next steps to breaking it down.

@ray benson
Ray, this guy needs a repair manual for a MS 260 .
Help is on the way .

 

[Sidecarflip]

Damn EPA and that stupid alcohol gas! I can't tell you how many bad carbs I have had to replace over the years.

Why I have a fairly large heated ultrasonic cleaner that has Berryman's B12 Chem tool in it. That stuff positively strips out all the e-gas gunk from a carb in about 15 minutes. I do use it with Simple Green degreaser as well for 'dunking' my handguns as well. Very worth while tool for me. I do my to be sharpened chain loops in it as well with a lye and water solution. Cleans them right off 100 %.

 

[Bob Hedgecutter]

It ran fine when I put it away a year ago.

What that tells us is- the fuel in the tank on the very last occasion you used it before putting it away for a year- was most likely straight gas.
Saws running straight gas or very low oil ratio gas run super good for a wee while- before they lean out fully, scream up in revs and die on the spot.
If you shut the saw down before the death scream- the damage was done, piston cooled and is now that undersized there is not enough compression to start.
Bet you it WILL pop and maybe run as is- with the hillbilly compression test of some straight oil down the spark plug hole to take up the slack. Will smoke like a mosquito fogger if it runs- but it will temporarily lift the compression and maybe see a pop or two.

 

[EchoRomeoCharlie]

See post 17

I know. I saw the picture of the torched piston.

Twas a joke.

 

[lone wolf]

I know. I saw the picture of the torched piston.

Twas a joke.

Straight gas sure is the most likely culprit, we will know more when he tears into it.

 

[lone wolf]

Try this. page 37

 

[OM617YOTA]

Too bad he dumped the old fuel already, would like to see what it looks like in a glass jar, held against a white background.

 

[Sidecarflip]

I have a bad feeling the cylinder is junk as well and who knows how much got into the bottom end as well. Also curious as to what he did to the carb as far as cleaning it. He said he did but never elaborated as to what exactly he did. No matter what he decides to do, it will be an involved job. I need to make some popcorn for this thread....lol people, in general never admit to anything that shows negligence on their part. Human nature.

One thing about repairing a 2 stroke and that is, unlike a 4 stroke all of them are pretty simple, so long as one posses the correct tools that is.

I'm gonna sit back and read along at this point....

 

[Bob Hedgecutter]

If it's really necessary, I'd tackle putting in a new cylinder and piston. But I'd like to see how she runs first. The scoring on the cylinder looks terrible in the pic I know, but it's actually a lot smoother than it looks. I want to check the compression - but the valve on my tester is missing, got one coming later today.

Don't battle it- most the guys that have replied have a fairly good idea of what they are talking about- most of us have/or will do it to their own equipment at some stage if you play with 2 stroke mixed fuel and equipment- I have, ruined a good saw on one tank of straight fuel- it happens. There are thousands of machines in service shops and or skip bins from the exact same thing- you are not alone.
Accept what you are reading in replies- decide on a course of action and set about doing it.
Plenty of guys here to walk you through a 260 rebuild.

 

[lone wolf]

Too bad he dumped the old fuel already, would like to see what it looks like in a glass jar, held against a white background.

Well yeah but it's almost a forgone conclusion.

 

[Bob Hedgecutter]

Too bad he dumped the old fuel already, would like to see what it looks like in a glass jar, held against a white background.

That is not so easily done here unless the operator was using green or blue dyed oil- our 91 octane is dyed red and very close to red oil colour before oil is added!

 

[ray benson]

Ok ok ok, let me get my head around the next steps to breaking it down.

Check your inbox for an ipl and service manual.

 

[ZeroJunk]

Buy a T handle T27 Torx driver. If you plan on taking the carb and manifold off masonry twine works well to pull the boot back through the carb housing. I would take the manifold and impulse line anyway because a hole in either of them could lean you out. Examine closely. Try to save your base gasket, but they are cheap if you can't. The little orange Stihl screw drivers with a little slot filed near the side work ok for installing circlips. Buy some extra ones.
And Band Aids for when you poke a hole in your finger. The little red ring thingamjigs to compress your rings are pretty cheap. The Stihl circlip installer is the cat's meow, but can't see buying one for one saw.
Some muratic acid from Lowes will help desolve the aluminum off the Nikasil. Don't breath it.
The transfer will most likely all be on the exhaust side
Use some sandpaper and your finger to get the transfer out. Don't leave ANY.

Anyhow, you will be surprised how simple it was.

 

[deanbrown]

I'm gonna put possible blame on my honda trimmer for this mess. Its little 4-stroker has its own 1 gallon gas can with no mix. Maybe I used that once for the saw, who knows.

The thing is it seemed like a long process of deterioration, with the saw just getting more and more difficult to keep running. In the end it would stall out if I put it down, or if it was hot, or if I picked it up too fast. Something leaking and making it too lean maybe?

 

[trains]

my money is on the 4 stroke fuel can mix up.
you said it was getting more and more difficult to get running, thats when the scoring was happening.
its just that you have now found it.

your going to learn how to fix it, lots of good advice here, very knowledgeable people here, so listen to the advice, report back on each step, and in time, you will have a good running saw again, and gained knowledge and experience at the same time.

 

[lone wolf]

I'm gonna put possible blame on my honda trimmer for this mess. Its little 4-stroker has its own 1 gallon gas can with no mix. Maybe I used that once for the saw, who knows.

The thing is it seemed like a long process of deterioration, with the saw just getting more and more difficult to keep running. In the end it would stall out if I put it down, or if it was hot, or if I picked it up too fast. Something leaking and making it too lean maybe?

We will know when we see both sides of the piston.

 

[lone wolf]

Buy a T handle T27 Torx driver. If you plan on taking the carb and manifold off masonry twine works well to pull the boot back through the carb housing. I would take the manifold and impulse line anyway because a hole in either of them could lean you out. Examine closely. Try to save your base gasket, but they are cheap if you can't. The little orange Stihl screw drivers with a little slot filed near the side work ok for installing circlips. Buy some extra ones.
And Band Aids for when you poke a hole in your finger. The little red ring thingamjigs to compress your rings are pretty cheap. The Stihl circlip installer is the cat's meow, but can't see buying one for one saw.
Some muratic acid from Lowes will help desolve the aluminum off the Nikasil. Don't breath it.
The transfer will most likely all be on the exhaust side
Use some sandpaper and your finger to get the transfer out. Don't leave ANY.

Anyhow, you will be surprised how simple it was.

Wait till you put some of that Muriatic acid in a bucket that had chlorine for the pool in it, OMG!!!!!!!!!!

 

[ZeroJunk]

Wait till you put some of that Muriatic acid in a bucket that had chlorine for the pool in it, OMG!!!!!!!!!!

I pour it is a shot glass. Seem to have plenty of those for some reason.