New Stihl MS261 - uneven chain tension

[PV Hiker]

@IntegrityCarpentry you might be onto something.?.. I don't remember mine looking like his.

 

[Patrick1903]

Yes a rim sprocket can be run either direction. Some will see wear and flip it over to get more life out of it.

Just wondering if op tried reversing it and if any difference was noted.

 

[Amin_1992]

Thanks all for responding! It's looking more and more like a sprocket issue. I have a cheapo Chinese sprocket coming today from Amazon just to see if installing that changes anything, while I wait for my dealer to get the OEM sprockets in (1 week).

We'll see if it changes anything or not

 

[Hundred Acre Wood]

Thanks all for responding! It's looking more and more like a sprocket issue. I have a cheapo Chinese sprocket coming today from Amazon just to see if installing that changes anything, while I wait for my dealer to get the OEM sprockets in (1 week).

We'll see if it changes anything or not

You may get lucky, but in my experience the knockoffs are even more inconsistent in quality. I pay the Stihl tax to avoid the hassle most of the time.

 

[huskihl]

I’d put it in wood and see if it sorts itself out. It’s common probably 50% of the time with a new sprocket and chain. After the first tank when re-tensioning the chain the problem is gone

 

[Amin_1992]

I dont plan on using the aftermarket sprocket - just wanted to install and see if anything changes and if it proves that the original sprocket is the problem. Spending 8 bucks was worth setting my mind at ease while I wait for the new OEM ones haha.

@huskihl thanks for the tip but I've ran through an entire tank of gas and nothing has changed. Good to know though that 50% of sprockets are that bad - glad I ordered 2 more!

 

[Hundred Acre Wood]

I dont plan on using the aftermarket sprocket - just wanted to install and see if anything changes and if it proves that the original sprocket is the problem. Spending 8 bucks was worth setting my mind at ease while I wait for the new OEM ones haha.

@huskihl thanks for the tip but I've ran through an entire tank of gas and nothing has changed. Good to know though that 50% of sprockets are that bad - glad I ordered 2 more!

They're not made of butter. They take a while to wear in. That's why in post #7 I said "a few hours". Put a few more tanks through it.

 

[Amin_1992]

Ultimately I'm going to do exactly what you prescribed @Hundred Acre Wood ! My curiosity just wanted to ensure that it is in fact the sprocket. I'm not going to get 3 tanks through the saw in at least 6 months (lot going on, already got my wood cut on the old saw for this year) so I wanted to just make sure it was in fact the sprocket so that, 6 months from now, I dont realize it's something worst.

As you said I have 2 years of warranty but I'm also a worrier and just wanted to see what was happening. Appreciate your help and everyone else's here!

 

[IntegrityCarpentry]

They're not made of butter. They take a while to wear in. That's why in post #7 I said "a few hours". Put a few more tanks through it.

So are you saying some misformed sprockets that are off, by running them, the off teeth will change forms and sometimes get right? Not being sarcastic. The little I have seen some sprockets are off and others are even and right.

 

[Amin_1992]

So are you saying some misformed sprockets that are off, by running them, the off teeth will change forms and sometimes get right? Not being sarcastic. The little I have seen some sprockets are off and others are even and right.

That's what I'm thinking. After hearing @Hundred Acre Wood explain that, my thought was that the tighter parts of the sprocket would wear more than the location making the chain looser, eventually making it more true?

 

[Hundred Acre Wood]

That's what I'm thinking. After hearing @Hundred Acre Wood explain that, my thought was that the tighter parts of the sprocket would wear more than the location making the chain looser, eventually making it more true?

Yes. The teeth will wear over time, highest spot first, as long as they're not grossly out of round.

This is a spur sprocket image from Stihl, but the idea is the same as a rim sprocket. I have old 8T .325 spur sprockets from my 30 year old 034 that look worse than that but I still ran them when I didn't have a replacement on hand. Eventually they wear enough you need to replace them. That's the reason rim sprockets were invented, to make replacing cheaper/easier.

 

[Amin_1992]

Thanks for sharing the pic!

 

[Patrick1903]

Thanks for sharing the pic!

@Amin_1992 have you reversed the rim sprocket as a test?

 

[Amin_1992]

I did not reverse it as I feel like my other experiment already settled it's the sprocket. I uninstalled the sprocket, kept the drum in the same orientation, and reinstalled the sprocket in a different orientation.

To put it more simply, I marked the sprocket location where loose (a notch with a sharpie at 5 oclock), kept drum in same location (notched at 5 also) and then reinstalled sprocket at like 8 oclock orientation based on notch. Chain was loose at 5 oclock again. Did the same thing and put sprocket at like 12 noon. Loose spot is still with sprocket at 5 oclock. I feel that shows it's the sprocket specifically.

 

[PV Hiker]

my rim sprocket looks like yours so no need for a picture.

What you should try is a different chain. A new chain drive links will be ruff and need to be run at speed to wear off the ruffness. Then see if you have the same issue.

 

[Amin_1992]

Hey bud, I did buy a second chain already. Same issue

 

[Amin_1992]

Just got an update from my dealer. The rim sprockets for a 261 (325-7 tooth) are back ordered from Stihl with no estimate on a date... how wild is that? I thought theyd have a thousand in stock at the dealer and didnt expect for them to be freaking back ordered...

he said his best guess based on recent back orders is 2+ months - wtf?

 

[Amin_1992]

Just wanted to give another update. Got the Chinese aftermarket sprocket today and installed. Definitely not high quality but wildly enough, it was more symmetrical than the Stihl one! Had some ups and downs but overally kept the tension far more consistent than the Stihl. Kind of nuts.

Installed the original sprocket again and again, loose spots on same marked spot. It's definitely the sprocket. Wonder when I'll get my back ordered replacement though... Lol

 

[huskihl]

Warranty is gonna be used up waiting for parts

 

[REJ2]

The joys of being able to buy OEM and Oregon parts online from hundreds of authorized sellers was paramount to me when i went saw shopping 14 years ago. Always buy rim sprockets a half dozen or more at a time. It hurts to hear these storefront dealers lead times on common wear items.