Stihl MS250 mixture screws?

[nyone]

Make sure you check the spark arrester. They do clog up.

 

[WranglerX]

My MS 250 got a bit cranky to run.. Tweaked the idle mixture and idle speed screws by the manual and it runs great again... Does not seem to be sensitive to old or new fuel....

Dale

 

[circled]

When my MS250 gets running rough I pull the spark arrestor and burn it clean, then add about an ounce of seafoam to the fuel. After a minute or two at WOT it always seems to return to normal for another year! Maybe dumb luck, but it works for me. Good Luck!

 

[dodge man]

I suspect I need to pull the spark arrestor. I assume this is the thing that looks like a muffler? How do you burn it clean?

 

[RandyT]

I suspect I need to pull the spark arrestor. I assume this is the thing that looks like a muffler? How do you burn it clean?

Propane torch works wonders on those arrestor screens. Just something to get them hot enough to burn off the deposits.

 

[Rebeldad1]

My MS250 had problems and I just replaced the carb. Seems to me it was under $25.00 for a new one.
Almot ALL my 2 stroke engines quit having problems when I switched to Pure fuel. I add Seafoam, PI fuel conditioner and Octane booster to my 5 gallon can. I use this on all the small engines. Mower, generators etc. I also spray the carbs once in a while with PowerFoam as a maintainence cleaner. I use a marine (Amsoil) 2 stroke 100 to one mix with this for the saws.

 

[nyone]

What octain where you using? Most stihl saws require 91*. I have been using 93* e0 fuel in all my small equipment as well as fuel stabilizer.

My problem with the spark arrester getting clogged happened to be from me useing to much oil in my mixed fuel. Check your saws spec, if your mixing correct maybe it's time to change oils.

 

[ericm979]

So look for an older Husky with the same model engine and buy an adjustable carb for the older model. They run about $40 on the internet.

I'm embarassed to say that I didn't think of that. I bought a $10 ebay carb with adjustments and went to put it on today. Unfortunately I'd forgotten that the blower I have is a "CARB II" model from the early 2000s and has a funky two bore carb. The small secondary bore goes to a tiny reed valve in the intake manifold and then there's a hose to the crankcase. It looks like some sort of stratified charge thing. The regular type carb does not bolt on to the manifold. I might be able to find the non strato manifold parts to adapt it but since the parts are from the 2000s and many are no longer available it might be tough. Bummer, it was a good idea.

 

[dodge man]

I’m running 91 octane and Amsoil 2 stroke oil at 50 to 1.

 

[dodge man]

I took the spark arrestor apart and I don’t think that was the problem. It is generally running good but still will not quite idle but it does throttle up. I suspect it is just sensitive to needing fresh gas. When I had the spark arrestor off I could see score marks on the piston through the exhaust port. I am not sure if that is normal or not.