MS 250 can't pull

[Hipa Store]

Hi,
First post here.
MS 250 had for years now. Yard worker decided wasn't running smooth so adjusted carb. Then could never get it to accelerate, would die when trigger pulled. Calls to Stihl and setting it back to initial settings no help. Sat for 6 months and tried to work on it again. Cord will not pull through to try to start. What I read at the time said could be ignition or timing. Set timing gap to 0.3mm. Pulls freely with spark plug removed. No buildup or scoring on piston or walls. Can only pull cord maybe 2 inches the locks pull like hydrolock. Can pull real hard to get past stoppage, but only pulls 2 inches then stops like hydrolock again.
Bought new carb, ignitor, flywheel, muffler, and installed all. All fuel been drained maybe a month ago. Turned upside down with carb and muffler off and spark plug removed and pulled cord 6x to make sure no fuel or water or whatever in cylinder. Can turn flywheel easily by hand with plug out. Took muffler off again, installed and tightened plug and cannot pull cord past 2 inches of starter cord. Took cord assembly off and with plug tight can move flywheel counter clockwise through full rotations by hand. Can feel compression build and can move past by hand. Put cord assembly on and locks up every 2 inches of rope pull. Makes no sense to me. Cord pulls freely when not attached to saw.
Anyone know what is happening and how to fix it. Stihl corp tech support no help. Local dealers won't even answer a question if it's about mechanics or running.

[Eugene Dixon]

I had to clean the starter coil system thoroughly on my Husky 65 to overcome a hard to pull cord.

Still, for Stihl stuff, I would search/review Chicanic's YouTube channel. She seems to know what she is doing around a 2-stroke engine.

[John TenEyck]

You might get more help over at Forestry Forum

John

[Tom M King]

Did you clean the spark arrestor screen in the muffler? 250's are known to be hard pullers. It has to be able to breathe out as good as it breathes in.

If the screen hasn't been cleaned, which the description of how it runs sounded like, take it out. Hold it with an old pair of pliers, and heat the whole thing red hot with a propane torch. When it cools, rub it between the fingers of an old glove. All the gunk should fall off as ash, and you should be able to see through the screen. Put it back in, and if the carb adjustments haven't been screwed up, it should run like a new one.

The Stihl dino 2-stroke oil, in orange bottles, is bad for clogging the screen.

[Hipa Store]

I just replace the spark plug.

[Hipa Store]

Did you clean the spark arrestor screen in the muffler? 250's are known to be hard pullers. It has to be able to breathe out as good as it breathes in.

If the screen hasn't been cleaned, which the description of how it runs sounded like, take it out. Hold it with an old pair of pliers, and heat the whole thing red hot with a propane torch. When it cools, rub it between the fingers of an old glove. All the gunk should fall off as ash, and you should be able to see through the screen. Put it back in, and if the carb adjustments haven't been screwed up, it should run like a new one.

The Stihl dino 2-stroke oil, in orange bottles, is bad for clogging the screen.
I just replace the spark plug.