Next problem with used ms261

[Henry E]

Bought a used ms261 a month ago. It wouldn't run right and prior owner put in a Chinese carb. It seems that created an air leak and the saw went straight to full throttle once 1/2 choke removed. I cleaned and put the original carb back in. Idles, accelerates and revs fine now.

Old clutch had a broken spring and retainer. And had a lot of gunk under the clutch.
I bought a new Stihl clutch and replaced the old one. Clutch drum spins about 8-10 times around when spinning by hand, with brake off. Drum rotate with engine speed even at an idle about 1/2 the rpm of my other saws. I would guess way under the 3000 rpm Stihl lists. But the drum spins. When I engage chain break, the engine is killed.

I inspected the old clutch and the new clutch. The two parts look identical EXCEPT that the Stihl part number is on the opposite side of the clutch. Like the central nut was put on backwards. My guess is that will not matter - BUT DOES IT?

With brake on, clutch drum doesn't spin. Good, that is how it is supposed to works.
But with brake on I can pull the started, but with each pull it gets harder. Like the clutch is starting to engage.
The clutch drum does have a lot of side to side play.
I did change the brake band along with the clutch and needle bearing today.
So the clutch, needle bearing and brake band are new.

- I checked the IPL and a couple videos to ensure I am putting everything the right way out and in the right order.
- new oem Stihl clutch
- new aftermarket needle bearing. Same problem with the original Stihl needle bearing
- old oem Stihl drum. Cleaned up the inside and outside pretty darn well. Not polished but smooth.
- idle speed is fine. Even idle set noticeably low, drum spins.
- chain break kills engine. Hence clutch drum and clutch are not disengaging when break applied.
- drum spins freely by hand
- drum has noticeable side to side play. Main bearing has no play.
- I can stop the drum from spinning by holding it with a rag while idling. But I hear clutch sliding against the drum when I do that.

Do I have a bad clutch with weak springs?
Would this cause chain brake to apply and not disengage clutch?
Should drum have noticeable side to side play? If no, how do I fix?

 

[Ozhoo]

Is this washer installed correctly?

 

[cus_deluxe]

Hows the drum bearing?

 

[blsnelling]

Crank end worn?

 

[Henry E]

Part 17 is installed with the concave portion toward the clutch (not the oiler). Thats the way I took it off, and everything I find indicates that orientation.

Drum (needle bearing) is new. Same result with the needle bearing I removed to put the new one in.

Crank end appears to be in very good condition.

 

[dmb2613]

It will have TOP stamped in it that goes to the top lol

 

[trains]

So you only cleaned the clutch drum #19 in the pic, but didnt change it, and it has an aftermarket clutch drum bearing too #18.
you mention it has quite a bit of side to side wobble, either its the aftermarket bearing, or worn clutch drum center.
New clutch center, but old clutch drum ? how is the wear on the clutch drum where the shoes engage, any lip ?

pics would help
T

 

[Henry E]

The clutch drum look pretty good. But may be the cause of the wiggle. I have an ms260 that I will try its drum on the problem 261.

 

[Stihldoc]

In addition to all the good things to check that have been previously listed, look at the oil pump worm gear. If it is binding on the crankshaft, it will turn the drum as surely as the clutch will.

 

[Henry E]

The worm gear spur has the tip broken off. So it was a little too short to reach the drum.

Turns out a ms260 and ms261 have different drums (xxx2900 vs the taller xxx2910) and needle bearings. The bearings fit back and forth. I tried the old and new 261 bearing. Both leave the original drum with a good 1/8" plus of tilt play with them. The bearing clearly doesn't fit well in the drum. With the drum out and the bearing in drum, I can see a noticeable amount of slop. So I will be ordering a new drum.

I checked the shaft and saw some wear. Just enough to convince me to expect the worst. Is the crank shaft hardened and the drum not, so that the drum is the sacrificial lamb (wear point)? Similar to how a snow blower has shear bolts to sacrifice themselves to save the drive shaft..... Or will I get the exciting opportunity to slit the cases, buy new gaskets, bearing, seals and crank?