stihl 261 chains loosening

[Rob Stringer]

hello all, i've recently had a problem with chains gradually expanding to the point that they are too loose for the bar (generally before the chain is worn out so pretty annoying) on my stihl 261 chainsaw. I'd been using plantoil bar oil with all my saws for at least 10 years without problems but have recently switched to stihl/husqvarna bio oil due to the price shooting up. I'm guessing its a problem relating to lack of oil but dont really understand it as i've never had this problem before. Anyone got any ideas? Thanks,Rob S

[Rob D]

15 minutes ago, Rob Stringer said:

hello all, i've recently had a problem with chains gradually expanding to the point that they are too loose for the bar (generally before the chain is worn out so pretty annoying) on my stihl 261 chainsaw. I'd been using plantoil bar oil with all my saws for at least 10 years without problems but have recently switched to stihl/husqvarna bio oil due to the price shooting up. I'm guessing its a problem relating to lack of oil but dont really understand it as i've never had this problem before. Anyone got any ideas? Thanks,Rob S

 

 

Have you checked the drive sprocket or drive rim? Do you dress the bar regular? Highly unlikely to be the bar oil you are using ie, I give it 2%

 

Let's see some pics of the chain and bar and drive rim pls

[spudulike]

The early 261s were prone to issues with the clutch drum bearing wear that can wear the oiler pinion arm significantly reducing the oiler output. I would make sure the drum bearing and oiler arm/pinion are in good shape....the arm can look fine but the end of it MUST sit in the outer clutch drum notch - it can wear off and looks fine but in reality, it isn't doing much. 

If this is all OK, make sure that oil is thrown from the bar tip when you rev the machine flat out and point the bar tip at a clean piece of wood etc.

The oil does have an adjustable output so make sure it is set to maximum if the above checks out.

[Rob Stringer]

Thanks for the replies, this is a newish saw so doesnt have problems associated with early 261. I dress the bar regularly and make sure the oil hole is clear. What would I be checking the drive sprocket for? (its not that old) I'll investigate further, quite hard to ignore when the chain has been fully tensioned and still hangs off the saw.

[GarethM]

A worn rim will have impressions, surface marks are fine but when it indented it will make for a looser chain and require more adjustment to take up the slack.

 

I should note it's a dark art getting tension just right as it will tighten and loosen depending on temp.

Edited October 19, 2023 by GarethM

[Rob Stringer]

Thanks, in this instance its gradually getting looser but not shrinking again when it cools down. Becomes a problem when the chain tensioner is at the end of its travel.

 

[htb]

What  make and model of bar and chain are you using? 

[GarethM]

End of travel, what bar and chain are you running?.

 

If anything it should be about 1/4-1/2 of the adjustment travel 

[Rob Stringer]

Yes, it starts out part way along its travel then gradually moves to the end as it gets looser. I obviously realize it shouldnt be doing this. Currently running standard stihl 14" guidebar with matching chain. In the time its taken to wear the chain halfway through its life its loosened to the point it cant be properly tightened on the bar its intended for (if that makes sense).

[GarethM]

14" should be 60 link, i run a 18" that's 74.

I'd count the links personally just for my own peace of mind.