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Stihl ms261 clutch drum issue?

BonScott46

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Noticed there were a couple of chips out of one of the slots on the rim sprocket on my ms261 along with the chain getting tight and going slack (hanging about 1/4 inch off the bar) as I would pull the chain around by hand. At first I thought the rim sprocket was defective but the problem persisted after trying two others. I am now thinking it is the clutch drum. Saw is about two years old, not abused and runs fine otherwise. Anyone else have this issue? Figured I would see what you guys think before I shell out 75 bucks on a clutch drum kit.
 

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I haven't noticed any issues like this.
 

BonScott46

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Take a good look at the drivers on chain. You could have a couple that are buggered and are not seating in rim.
They look fine. I checked two of the 3/8ths chains i was running. I also switched back to a brand new .325 rim and chain with the same result. I figure drum or crank?
 

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Any photos of drum?
 

huskyboy

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Noticed there were a couple of chips out of one of the slots on the rim sprocket on my ms261 along with the chain getting tight and going slack (hanging about 1/4 inch off the bar) as I would pull the chain around by hand. At first I thought the rim sprocket was defective but the problem persisted after trying two others. I am now thinking it is the clutch drum. Saw is about two years old, not abused and runs fine otherwise. Anyone else have this issue? Figured I would see what you guys think before I shell out 75 bucks on a clutch drum kit.
The drum or sprocket could be out of round. Or your crank is bent... hopefully not that one lol. I do notice the chain tightening and slacking a little bit on pretty much every saw I have if I spin the chain around by hand... so it’s somewhat normal I’d say. But if it’s doing it a lot like you say then it might be a problem. Some pictures would be helpful for us to be able to better help you.
 
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RI Chevy

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What brand of chain are you using? Could be chain stretch.
I am just thinking outloud. I realize you are an experienced cutter.
 

BonScott46

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I will get pictures in a bit. I can say that when I inspected the drum last I saw that the edge was poorly finished and uneven. I don't know if it is out of round though. I talked to my buddy today and he said that when he was working a contract clearing the railways all of the guys were having problems with the clutch drum/sprockets on the 261's. He said they were eating rim sprockets and the drums were generally crap. According to him guys started fitting 260 drums and that was fixing the problem.
What brand of chain are you using? Could be chain stretch.
I am just thinking outloud. I realize you are an experienced cutter.
That may be contributing to it but I swapped to a new chain of different gauge and brand with the same result, excessive slack in the chain.
 

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If your in there with the clutch drum off and looking around the bearing and measuring the shaft for wear, I think it’s only 1/2 a mm and it’s buggered.

remember to get some one to look at the shaft and clutch while you pull it over. To see if it’s bent. Make sure it’s switched off you don’t want it starting and trying to eat the break band. Ask me how I know ..
 

BonScott46

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Clutch bearing looks to be fine, no cracks etc.
3C4690EB-64BC-46C2-BC2A-A37BACF5C4AF.jpeg 36E39F21-E136-43B7-974C-4241F47BA3B0.jpeg B43029C8-E864-453A-B413-CC1798D443FB.jpeg 33D7B975-CCCC-4045-81EE-1739735E3685.jpeg B14FD00F-9C82-4260-B193-F64F26A8EBD8.jpeg
 

huskyboy

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Pull over the saw slowly and observe the clutch with the clutch drum off as you do that. Does the clutch spin round or is it moving up and down a little. If so your crank is bent.
 

huskyboy

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Also wiggle the end of the crankshaft and see if there is any play in the bearing. Turn the motor over and check in different spots. There should be ZERO.
 

huskyboy

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And do you have a picture of how much slop variation your getting at the chain?
 

BonScott46

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Also wiggle the end of the crankshaft and see if there is any play in the bearing. Turn the motor over and check in different spots. There should be ZERO.
I will check the crank/clutch tomorrow. If i can’t find any play/wobble i think it will be a new drum.
 

Wonkydonkey

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Your pics show the drum is not flat [3rd pic] , not sure what that would do but it don’t look right. Maybe create a wobble and vibe and wear stuff prematurely
I’ve copied your pic and just moved the side in a bit closer to hopefully show what I mean. Although it maybe the way you took the pic and has given the elusion
B2F9CD45-9823-470F-BD81-A6199B4E406C.jpeg
 

BonScott46

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Your pics show the drum is not flat [3rd pic] , not sure what that would do but it don’t look right. Maybe create a wobble and vibe and wear stuff prematurely
I’ve copied your pic and just moved the side in a bit closer to hopefully show what I mean. Although it maybe the way you took the pic and has given the elusion
View attachment 273478
Yes, that was what i was referring to when i said the edge was poorly finished and uneven.
 

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I upgraded all my clutch bearings to steel caged bearings. I have a V1. Only use Stihl or Oregon chain..325 and 3/8. Maybe there is an issue with chain tensioner?
Just shooting from the hip here.
 
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