Stihl 261C High Idle

[Meteor]

Hoping some more knowledgeable people can assist with this one.

I recently picked up a 261C for very little at auction. It was missing a few screws, clutch cover and clutch drum etc which I’ve replaced. since them, I’ve actually bucked up a tree with it to see how it ran and I was quite surprised how well the little 50cc saw did. But it has one issue. A high idle to the point where the chain just won’t stop and while it was fun to test out, it’s not safe to continue using as is.

I “think” it’s an older 261 and is labelled as a “261c” on the cover and chain brake label. Plus I saw a 2012 date somewhere. I’ve followed Stihl’s guide to reset the M-tronic carb using both methods. (I don’t know which one it is as there’s no labels with the “M” version on the saw.) I thought the original reset method worked as the idle had slowed down on restarting but as soon as I revved the saw, it wouldn’t return to low idle again. Tried the second method too and zero change there. Tried the first method again and no change for that attempt either.

Before I go pulling it to bits and pumping any more $$$ in, is there anything else obvious I should start looking for? I did see some other posts about the fuel filter and solenoid. The fuel filter looks like it should based on what I’ve read but I don’t know what I’m looking at with the solenoid. (I’ve requested the manuals in another thread on this site.) Any suggestions?

 

[DND 9000]

The first thing I would recommend is a pressure and vac test. Might be an air leak somewhere on this 13 year old saw. If any leaks are found, repair them. If you prepare for this test you can also inspect the piston and cylinder for scoring. After that I would replace all the filters and give the carburetor a good cleaning and rebuilt with a repair kit. Also check the fuel and impulse hose for any cracks. After that test it and see how she runs.

 

[coffeebrk]

Was the clutch drum genuine Stihl part?
Was the clutch itself also replaced?

 

[Meteor]

The first thing I would recommend is a pressure and vac test. Might be an air leak somewhere on this 13 year old saw. If any leaks are found, repair them. If you prepare for this test you can also inspect the piston and cylinder for scoring. After that I would replace all the filters and give the carburetor a good cleaning and rebuilt with a repair kit. After that test it and see how she runs.

Thanks for the suggestions. I should mention that the air filter is brand new and the piston / cylinder looks great.

I actually bought this saw because it was ugly and I assumed the piston was done and was wanting to teach myself to rebuild top ends. But once all the grime was cleaned off and I checked the piston, I gave it a crank and it fired up on the third pull. Couldn’t believe it! Aside from this idling issue, this saw turned out to be a little diamond in the rough. Well… hopefully.

 

[Meteor]

Was the clutch drum genuine Stihl part?
Was the clutch itself also replaced?

I got it from a local online supplier but you know what… it may not be. Clutch was not replaced.

 

[DND 9000]

One more possibility: Check the throttle lever and throttle shutter that they move easily and freely. The throttle shutter must not stay open if the throttle is not pressed.

 

[Gagliano7]

Just pull the cover and you can see if it is m-tronic.You will see the wiring by the carb and the solenoid as look from the back of the saw is on the right side of carb. That is where the wiring ends.

 

[Meteor]

Just pull the cover and you can see if it is m-tronic.You will see the wiring by the carb and the solenoid as look from the back of the saw is on the right side of carb. That is where the wiring ends.

Yeah it’s M-tronic hence the post. But from what I’ve read, there are different versions of solenoid etc.

 

[coffeebrk]

Do a pressure and vac test as suggested. You could also put a tach on it and see what its idling at. If it is within specs then most likely clutch. MS261 is a nice pro saw Ive got a couple of them. If the piston and cylinder are nice and genuine Stihl then its worth fixing it proper

 

[Meteor]

Do a pressure and vac test as suggested. You could also put a tach on it and see what its idling at. If it is within specs then most likely clutch. MS261 is a nice pro saw Ive got a couple of them. If the piston and cylinder are nice and genuine Stihl then its worth fixing it proper

Thanks. I don’t have the equipment to vac test the saw but I think I’m going to have to look into getting something. I do enough work on saws that I should probably have it.

I’ll also keep the clutch in mind but I think it’s unlikely at this stage. It sounds high and the first attempt at resetting did bring the idle down but it didn’t last. Putting the tach on it is definitely a good idea though so I’ll do that tomorrow.

 

[Gagliano7]

If it has the black solenoid it is an early version.

 

[oldbuzzard]

Need to replace the black solenoid with green or white no matter what.

 

[singinwoodwackr]

Need to replace the black solenoid with green or white no matter what.

Not necessarily. If it floods out, yup, but if it runs ok, I’d leave it.

Is the clutch drum clean inside? Crud in the drum, worn clutch springs or worn clutch shoes where the springs attach will cause the chain to spin when it shouldn’t.

 

[oldbuzzard]

A black solenoid is going to fail, just a matter of time (I guess if your saw gets little use it might last) So yeah you can leave it in there “cause it’s still working”, but will you have the spare with you when it craps out in the field? And it has some tiny parts, so do you want to be changing it in the field?

 

[stihltech]

It is idling high. How high?
Throttle linkage will disengage due to a worn rod. You will see and feel the wear on the rod.
Look through the carburetor when held up to a light. How much light is coming around the throttle plate when closed?
While a pressure and vacuum test is a must, there is a quick method without tools. Get a can of brake cleaner. Spray it around all seals. lines, intake boot, gaskets, etc. When the idle changes (usually quite noticeably) you will have found a leak.
And agreed on the solenoid. Get the kit from Stihl with the orange fuel filter. Very common repair.
Orange OEM fuel filters ONLY!!!!

Remember, you are diagnosing a system, not just one part.

 

[Gagliano7]

Also kit is cheaper than just buying solenoid. Make that make sense!