Chain sticks when turned by hand...?

[pileswasp]

Rims *are* a better solution in pretty much every case except the 261

 

Ran my old 260 on rims for a lot longer than the 20-odd days it took my latest 261 to get switched to a spur.

 

I am cursed with optimism, though, so I keep buying 261s in the hope they will one day be as trouble-free as that 260...

 

 

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[Stubby]

Rims *are* a better solution in pretty much every case except the 261

 

Ran my old 260 on rims for a lot longer than the 20-odd days it took my latest 261 to get switched to a spur.

 

I am cursed with optimism, though, so I keep buying 261s in the hope they will one day be as trouble-free as that 260...

 

 

Sent from my iPhone using Arbtalk

 

Not tempted by 550 or 560 then ?

[Toby in Buckinghamshire]

Ok, having spent a while turning the chain by hand I think there is a pattern of roughly every 7 drive links. Therefore I'm thinking that the sprocket is to blame. Although it doesn't seem massively worn and the wear seems even but I'll change it and hopefully that solves it!

 

Also checked that the clutch drum is spinning freely and it is. There also doesn't seem to be any meaningful play in it.

 

Also checked that there was nothing binding with either chain/bar combo and that's fine too.

 

It is definitely caused by tightening the bar studs down though which I can't understand; I can't think how the sprocket and bar nuts would have any effect on one another? Chain tension doesn't seem to have anything to do with it... 🤔

 

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[bmp01]

Sounds like a diagnosis. Have to wait for new sprocket to make it conclusive.

 

The bolting it up thing is a puzzle though. It sounds like the wear pattern is not in alignment with the chain but that would imply a change in the position of the bar or position of the sprocket. Even a spur sprocket can move a little so youd have to be out by quite a bit. And youve changed no components?

 

Couple of other things to try...

-Assemble the saw with the bar but without the chain, tighten down the side cover. Does the clutch still rotate freely? I'm sure it will but worth the time it takes to check.

-Back to normal assembly - If loose chain tension makes no improvement (it should have), maybe its nothing to do with sprocket. Are you pinching the chain drive links between the bar rails when the cover goes on? I know its across two bar and chain assys but are they all std components? New or old? Any damage to bar rails or where the chain enters the bar? Is the the clutch cover flat? Whats the wear pattern like on the clamping faces... that sort of thing.

 

bmp01

[eldon]

Toby, with the chain removed are the shoulders (that the bar sits back against as its datum) on the two clamping studs aligned?

 

I had a single bolt 241 previously and the chain got tight on that one. It turned out after a bit that the stud was slowly screwing itself (moving the shoulder) out and so when you tightened the clamp nut the locked up position was not in line with the sprocket and blade.

 

Just a thought and worth a look.

[Toby in Buckinghamshire]

Toby, with the chain removed are the shoulders (that the bar sits back against as its datum) on the two clamping studs aligned?

 

I had a single bolt 241 previously and the chain got tight on that one. It turned out after a bit that the stud was slowly screwing itself (moving the shoulder) out and so when you tightened the clamp nut the locked up position was not in line with the sprocket and blade.

 

Just a thought and worth a look.

Thanks eldon. Are you able to tell from the below image?

[lurcher4]

Morning all

 

I've recent bought a 2nd hand (but very lightly used) ms260. I have noticed when I turn the chain by hand having set the chain tension that the will rotate around the bar smoothly and then feels like it snags a little and takes extra pressure to move it, then it spins freely again. This only seems to happen when the front bar nut is tightened down. I'm not doing the front nut overly tight. Chain tension seems fine. And brake is definitely not on!

 

I have tried this with a used 15inch bar and chain and also with a brand new 18inch bar and chain, seems to be the same with each. But saw runs fine when started. My concern is that it could be damaging some part?

 

Some light wear to the sprocket but doesn't look too bad to me?

 

[ATTACH]219139[/ATTACH]

 

Like I said, this only seems to be an issue when the front bar but is tightened.

 

Any ideas/suggestions?

 

Thanks

 

Toby

had the chain start jamming on my stihl so drilled two small holes like on a husky bar by the end sprocket greesed the end sprocket like I would a husky and problem solved have a look at that end sprocket m8

[Stubby]

had the chain start jamming on my stihl so drilled two small holes like on a husky bar by the end sprocket greesed the end sprocket like I would a husky and problem solved have a look at that end sprocket m8

 

Yea but on 2 different bars ?

[bmp01]

Thanks eldon. Are you able to tell from the below image?[ATTACH]219169[/ATTACH]

 

It's not obviously out of line but we're only looking for a fraction of a mm, can't see that in a picture.

Put both bar nuts on the back stud, lock the nuts together then try to tighten the stud into the housing. If it moves you know it was loose. You'll have to remove it and loctite it in. Repeat on the front stud. ...

 

bmp01

[Stubby]

It's not obviously out of line but we're only looking for a fraction of a mm, can't see that in a picture.

Put both bar nuts on the back stud, lock the nuts together then try to tighten the stud into the housing. If it moves you know it was loose. You'll have to remove it and loctite it in. Repeat on the front stud. ...

 

bmp01

 

Be sure its not the type that fit from inside the oil tank and locate in square first ......