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Stihl MS250 hard to pull?

Started by yardiron, December 08, 2019, 04:16:36 PM

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yardiron

First off, this is my first post here, I've been reading here for a bit after inheriting a truck load of old chainsaws from a relative last spring.
I'm slowly going through them to see what's worth keeping, ans what is just parts.

One of the nicer looking saws is a Stihl MS250, the saw looks to have almost no use on it.
I had set it aside at first thinking it had a serious motor issue because I couldn't pull the cord.
Something made me toss it up on the bench the other day to see what ails it.
The thing turns over, but it takes both hands and a foot to pull the rope. Its not seized, its just that hard to turn over. I pulled the plug, and it spins over freely.
I screwed in a compression gauge and got 188 psi. (In comparison, an 036Pro I checked had 166 psi).
It pulls so hard against the compression that I can't believe the recoil string doesn't snap or pull out of the handle.
I had it running, once it fires up it runs strong. But even on a hot restart, its a bear to pull.
I basically am holding the rope in my gloved left hand and dropping the saw with my right to get it to turn over. The handle is too small to get a foot into to try it that way.

Before I pulled the plug, I was really expecting to find it hydro-locked or something but its just that hard to pull.

I somehow can't believe that they built saw that's this hard to pull start?

(My 036Pro pulls easier without using the decomp button).

Are these all this hard to pull?

moodnacreek

While I don't have the answer I can tell you that this is a common problem on Stihl's that sit. Because of all the carb. problems I keep about 5 saws on the mill floor that might run when needed. The 0ld faithful 024 and the 028 will pull hard if not started often, the 028 being the worst. I am not young and the 075 becomes impossible for me to pull if not started often. The Husky's [ that I am not crazy about] don't seem to have this problem.

sawguy21

What color is the plug tip? it should be light brown.  Pull the muffler to see if there is a heavy carbon buildup on the piston. With the air filter off try spraying Sea Foam or diesel fuel down the carb throat but don't overdo it. moodnacreek that 075 is a beast on the best of days, I don't have fond memories of them. :D
old age and treachery will always overcome youth and enthusiasm

ButchC

The 250s are notorious for hard pulling but yours sounds excessively so. I agree with  carbon build up as has been suggested.
Peterson JP swing mill
Morbark chipper
Shop built firewood processor
Case W11B
Many chainsaws, axes, hatchets,mauls,
Antique tractors and engines, machine shop,wife, dog,,,,,that's about it.

moodnacreek

Guess I cut in front of Yardiron, anyhow thanks Saw guy and Butch C. Got the seafoam on the shelf.

yardiron

The spark plug is tan/brown in color, it looks to be burning pretty good. The top of the pistion looks pretty clean using a bore scope. I don't think its got a of use on it.
It fires on the second pull every time, and starts and runs on the third or fourth. Its just that its nearly impossible to pull.
I've got four other Stihl saws here, an 029, 036Pro, 015L, and an MS200T, only the 36Pro pulls this hard and only if I don't use the decomp button.
Once the 250 is running, its fine. Subsequent starts are just as hard.
When I first found this i thought it was seized or 'tight', but once I pulled the plug I realized its all compression.
Ive got one other saw that pulls almost just as hard, and older Husqvarna 266.
I'm 6ft 4in tall with size 17 boots, so putting a foot in the handle area isn't an option, or do I think it would help. With the saw in a vise, I still can barely pull the rope against the compression stroke. The only way I can get it to start is to grasp the recoil handle with a gloved hand and drop the saw with the other. I used the saw on Sat. to cut up some down branches, it runs and cuts good. No smoke, no noises. The piston sides look clean too.

Al_Smith

Size 17 boots  :o . It could be nothing more than the starter drum bushing worn or missing causing the drum to run eccentric .It happens 
I had that happen on a Husqvarna 2100 CD and that's 99 cc .I just turned a brass bushing for it on my lathe . 

sablatnic


Al_Smith

Geeze I just looked it up on flea bay .Drums are cheap but they are only about 2.75 " .It isn't any wonder they pull hard .I'd about bet my weed wacker has a larger drum . 

yardiron

I took the recoil apart, I don't see anything wrong in there. The rope is new, 3.5mm black and orange recoil rope off a spool I found on the bench in the back garage.
I tried just turning the motor with a socket and a 3/8" Snap On wrench, about 7" long and its nearly impossible to turn the thing over with a ratchet without the ratchet nearly busting your hand as it snaps over TDC.
There's definitely an issue here with a lack of mechanical advantage when cranking the engine. But it looks like its built into the design?
I've got other homeowner saws, a few I bought new, and none of them have this kind of compression.

As far as bending down to start a saw, with a foot in the handle, that's not happening, I haven' t been able to bend that way in decades and my food simply will not fit into the handle area. If I put it between my legs and tried to pull I'd likely bust my self in the nuts. With a gloved hand, dropping it seems to be the only thing that works and even then it nearly rips my fingers out. I tried swapping the handle out for one for a snow blower but it broke the handle in a couple pulls. Even when it get it to turn over dropping it, I only get the rope to move about half way. The saw usually starts so its not an issue that way.

The thing spins over smooth as butter with the plug out, even with the compression gauge in the hole its tough to spin over, it may have more than the reading I got because I wasn't achieving much RPM during the test.

My 036Pro is hard to start without the decomp depressed but its half as hard as this MS250.
I certainly realize that at my age I'm not what I was at 20 something but I'm also no 90 lb weakling. At 6ft 3in tall and nearly 400 lbs I should easily be able to start an average homeowner saw.
My 029, 036, 036P, all start with ease. They have noticeable compression resistance but they don't cause pain or any issue getting them to turn over.

I can't imagine the average homeowner being able to start this thing if this is how its supposed to be.

Al_Smith

I'd say it would be unusual to have that high of compression pressure .I have no idea what could hang it up so I think I'll just watch and see if you find anything .I'm out of ideas . ???

moodnacreek

So when that ms 250 was sold new how is it that it was not returned? Something is being overlooked. I wonder how many extra sparkplug gaskets you could get on it. 

stavebuyer

I had a MS250 as a "chore" around the house saw for several years. Went to my mill for employees to use to cut ties ends off. Was the only saw the thieves didn't steal when they broke into my tool trailer at the mill. It then cut firewood everyday for another winter until I gifted it to the employee running it. He still uses it around his house. I replaced it with a an 026 that's been to the shop several times and then replaced the 026 with a 261.

The "old 250" was a cheap saw, but a good one. In all that use I never noticed it being hard to pull, When cold it sputtered on the 2nd pull and started on the 3rd. When hot it started with half a pull. Maybe I just got lucky, but it was an excellent saw.

Jack S

  Just a thought if your saw has a decompression release remove it inspect it and make sure it is releasing the compression when pushed in.

 

pineywoods

Sounds sorta like a rebuild sometime in the past using a wrong piston or connecting rod.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

JW IN VA

 Hope you can find an answer.The 250 is a great little saw.Much more saw than it's size and price point would lead you to think.I bought one for a backup,brush cutting, limbing saw and have really been pleased with mine.

Al_Smith

My curiosity got the best of me so I looked up the IPL which is shared with the 021,023 and 025 .Assuming the MS 250 is in fact an 025 .
At any rate it only showed two pistons,40 and 42 MM .Two crankshafts 28 and 32 MM stroke .One evidently came apart in some strange way because it showed a separate  rod and bearing cluster .The other a standard pressed together crankshaft -rod assembly ,for all intents not repairable .Evidently this assembly being used for the 023 and 025 ,32 MM.
So having rambled on about it unless something else fits in it I don't see how the wrong parts would have gotten in to it .

luap

I don't have an answer for the hard pull but as far as not fitting your boot in the handle try this -put a stick through the handle that's long enough that you can put a foot on each end and then the saw is held so you can pull on it. I guess if you can't bend over this won't help you unless you can kneel down on it.  I read on here somewhere where someone drove the wheel of their machine on one end of the stick. I have a friend in his ninety's that showed me the stick method. Usually my problem with motors is not enough compression.

Al_Smith

I don't know if this is even possible .The piston of an 024 being 42 MM might be able to get stuffed in an 025/MS 250 by mistake .It  uses the same pin size ,M 10. 
If so and that did happen the height from pin center to face might be off ,too long  .

moodnacreek

When I lost the frock on the old 024 it wiped out the cylinder. Took a cyl. of a newer 024 and  the piston hit the head so [you guessed it] I filed the top of the piston and got Me a high compression 024.  Just something more to consider.

yardiron

I tried a couple of things today just to be sure the issue isn't something 'wrong' with the saw.
I first removed the muffler completely, tried to pull the rope, and that made no difference.
I then rotated the motor till the piston was up top, then I filled the combustion chamber with sea foam and let it sit all day. My thought was that maybe the piston was clean but there could be some carbon above the piston. After 11 hours of soaking, I dumped out the Sea Foam and it came out almost as clean as it went in.
The spark plug is likely the original, a Bosch WSR6F. After soaking all day, I put some marvel oil in the cylinder and worked it in a bit by hand so it wasn't going to start 'dry' after soaking it with Seafoam.
It still pulls just as hard.
The guy at the Stihl shop told me to buy a recoil handle for a rescue saw but they didn't have one in stock, but I'm thinking it may get in the way on such a small saw?

The saw runs great overall, once its started, its easy to use and has great power. Its got more power than my 029, and its far lighter.
I really don't think this saw has many hours on it. It still looks new, there's no dirt or dust build up and the original bar shows no wear on the sides.

Jack S

yardiron,
   have you verified the decompression release is relieving  compression or doesn't this saw have this feature? I haven't seen any mention in your posts that this has been checked.  Sorry if I missed it      John

Al_Smith

I have rescue saw handles on a souped 038 mag ,Husky 2100 CD and and 084 Stihl .
What the hey ,if that fixes it call it a day .

chuckp

I have 2 husky 61's that have developed the same problem. I'd like to learn a fix for this problem. Impossible to pull start normally, I have to use the two foot and a stick method too.

Al_Smith

I've usually  seen them get easier because the rings wore out .The exception being as if they got harder it was just because I became older .That's better than the alternative I suppose .< play on words . ;)

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