Nose sprocket of 660 gets blocked

[Blah]

We've had the 660 and 661 out quite a few times over the last couple of weeks and notice the nose sprocket on the 36" bars is getting blocked.

 

Sometimes it stops the chain altogether, sometimes it's just noticeable when rotating the sprocket by hand. Don't notice this at all running on 25" bars.

 

Tends to be a right faff to get it running again, usually a bit of wd 40 and / or chain oil and a bit of faff can get it running again.

 

Not entirely sure why this is happening. Any good ways of avoiding and / or getting it working again?

[htb]

Think 660 could be had with high output oiler. BY blocked do you mean with sawdust, is it your cutting style. Find it happens when chogging down, especially if cutting right through from one side and weight of chog tries to nip bar.

[Stubby]

Is the oiler turned up to max ? Also I think there is an up rated oiler for longer bars .

[billpierce]

Had a few bigger 3/8 stihl bars do this. Dismantled and oiled sometimes tapped free with a toiny hammer and they seem to work again, but will stop again in certain wood (ash often).when its siezing often, up a tree having to drag the chain up and down on an edge of somethign does your head in quick smart.

Reckon the sprocket bearing is borderline knackered. Expect it may have had a good pinch at some point. You can replace them usually. Think robd done a video on how to do the rivets on the nose sprocket

[Wolfie]

I tend to change my cutting style when using my 660 or 084.
I run the chain a little looser than norm and don’t constantly keep it under pressure throughout the cut, i’ll perhaps let it cut for 5 seconds then back off for a second or two to let the dust clear from the chain.

[Stubby]

Running full skip chain may help ( if you are not already ) .

[18 stoner]

Many years ago I experienced the same and managed to cure it on my 660.
In short you need skip chain and high output oil pump.
Basically there are too many cutters in one length of a 36” bar for the takers to clear the sawdust.
The skip will have less cutters overcoming this but the saw will cut more freely therefore higher speed.
As for the oiler I found due “not quite enough” oil getting out there, the bar/chain got slightly warm. It wasn’t really hot but enough to nip the chain up, this compounded the problem.
I know Chainsaw Bars will supply the best price skip, as for the pump, I got mine from my Stihl dealer.

[spudulike]

I found burying the complete bar in woods like oak would do it. As others have said, turn up the oiler, you could try thinning the oil a bit if it is a bit gloopy and the weather is cold.

There is only one oil pump on the IPL BUT two pump pistons, the one that should give more oil is the Australian spec  -1122 647 0602 rather than the normal 1122 647 0601 UK/US version - you will need to strip the oil pump apart and fit the new piston but it may be an answer on the longer bars.

[wicklamulla]

14 hours ago, Wolfie said:

I tend to change my cutting style when using my 660 or 084.
I run the chain a little looser than norm and don’t constantly keep it under pressure throughout the cut, i’ll perhaps let it cut for 5 seconds then back off for a second or two to let the dust clear from the chain.

good advice right there.

[stihlmadasever]

You should be running at least a semi skip chain on a 66 with a 36" bar.

Oiler turned up.

We run 25's on ours,just better imo.

Big bars are a lot of fannying around up the tree

Edited January 26, 2019 by stihlmadasever