Chain binding in bar

[Kogafortwo]

I was running my newly ported 46mm Stihl 028 a couple of weeks ago taking down trees for neighbors (they paid me in beer and my 13-year old son in cash).

The saw ran great, but for some reason the chain kept binding up on the bar and I had to take the bar off, clean out under the bar cover, let things cool a while, etc. and then reassemble. Then it would turn free again. The clutch was not binding. The sprocket is worn, so I will replace it, but I don't think that was it either. The chain actually seemed tight in the groove.

It is a nearly-new full chisel Stihl chain (RSC) on a 20 inch bar. Never had this problem before. I didn't pinch it in the cut or anything, and this bar has worked fine before.

Any ideas? Got a co-worker who wants his tree taken down soon, and he is offering beer PLUS steak! So I need to be ready to run. The 026 will do the job, but the modified 028 is more fun.

 

[watsonr]

Is the oiler working? Also, a dull chain will generate more heat.

 

[rmh3481]

If the oiler is working, you may have picked up an odd size chain. For instance a loop of .058 gauge when you needed .050? Take a close look at the bar and chain numbering. If you need help decoding the numbers, post them and we can tell you. Otherwise, has the chain been thrown or have any damage? How bad is the sprocket?

 

[nmurph]

I think you have already diagnosed your problem: worn sprocket.

 

[SawTroll]

The saw ran great, but for some reason the chain kept binding up on the bar and I had to take the bar off, clean out under the bar cover, let things cool a while, etc. and then reassemble. Then it would turn free again. The clutch was not binding. The sprocket is worn, so I will replace it, but I don't think that was it either. The chain actually seemed tight in the groove. .......

Could be a maintenace issue with the bar rails, but it could well be the worn drive sprocket that is the main reason. Cleaning out under the clutch cover isn't enough - you should clean between the rails and clean the oiler holes as well.
A wider gauge chain isn't only possible if the bar rails are very worn on the inside, so harly the cause in this case - but make sure the chain is the right pitch!

 

[Kogafortwo]

Can't find the right sprocket!!

Help! I went to Ace for the sprocket. They had one listed for the 028, but it doesn't fit. It is a one piece clutch drum and wide sprocket teeth sticking out the inner chain brake cover.

My old sprocket is circlipped onto the clutch drum with the bearing inside it. It's not a rim sprocket, but it is separate from the clutch drum. It is driven by the clutch drum by a machined drive-dog arrangement on the inboard side.

This is probably related to this saw being one of the first generation, with the really old chain brake style.

Part number assistance and parts source please!

 

[Dan_IN_MN]

Which clutch does your drum 028 have?

 

[Kogafortwo]

Which clutch does your drum 028 have?

Hey Hobies,
I have the clutch and sprocket combination that is NOT shown in this IPL. I have the same IPL and tried to look it up. The clutch drum is the one between parts 40 and 41 on your page, and that does not show the sprocket that engages with the slots in it.

If it helps any, I have the old non-crossover style chain brake.

 

[Kogafortwo]

Bad news - Ace definitely cannot get the old sprocket for me. The parts guy showed me a service bulletin from 1981 with a whole kit that replaces the old style sprocket and drum and chain brake cover. And he said most of these old parts do not show up in his parts search anymore.

So if anyone knows the piece I am talking about And has one, or two, I am interested.

 

[sefh3]

Take a few pictures of what you have and post it here. I'm not aware of a third option for an 028.

 

[Kogafortwo]

I'm going to run the saw today along with the 026 and my son's 011. I'll see how it holds up with the bar cleaned up and the oil holes cleared. When I take it apart to clean it up tomorrow, I will take pictures of the 028 sprocket and lcutch drum and post them here.

 

[Chris J.]

There have been several threads & posts regarding upgrading the 028 sprocket, most folks here seem to consider the upgrade worth the $$. Also, if your sprocket is bad you're damaging the drivers every time you use the saw.

http://www.google.com/#hl=en&sclien....,cf.osb&fp=76b71a3030273bc6&biw=1093&bih=440

 

[StihlyinEly]

Also, if your sprocket is bad you're damaging the drivers every time you use the saw

Exactly. And damaged/burred chain drivers will bind in the bar rails even if the chain is the right gauge for the bar. If it were my saw and I had other saws (as you do), I'd let it sit until I got it figured out. No point adding to whatever damage may already have been done.

 

[Kogafortwo]

I agree with y'all - I will fix it right. I will look for an upgrade kit so I can put a rim sprocket on it. A $6 rim is an easy maintenance expense. A $30 clutch drum+sprocket always makes me think twice.

By the way - had a frustrating day cutting yesterday. Every one of my saws is between 20 and 30+ years old, and every one of them got cantankerous with me. Plus what I thought was going to be a one-trunk easy takedown turned out to be:
1. First - a small ratty cedar that was in the way had to get cut down and cut up
2. Second - a long side-hanging branch of the tree we needed to remove had to come down. It turned out to be as much work as a whole small tree, since it fell in the brush. And my 026 got caught in the kerf and fell to the ground when the branch broke free. But no harm done.
3. Then the main event - also fell in the brush and had to be cut out piece by piece.

But it was still a good day - the friends we did it for served grilled steak beforehand, pizza afterwards, and they, their neighbors, my son and Mrs. KG42 all helped haul branches out so "all" I had to was run saws. And Mrs. KG42 drove us home in the evening so I could enjoy a couple of IPA's to wash down the sawdust in my throat.

Today I am sitting in front of the computer. And more beer is in the fridge.

 

[Kogafortwo]

parts availability

OK, here is the deal: I need ORF-30384x from Baileys, and ORF-37517. (Note part number prefix changed from RD-... and DSB... to ORF).

The kit does NOT include the chain brake dust cover with the larger hole. For that, I need Stihl 1118 021 1104. They are sold out or obsolete all over the place.

I DID find Stihl 118 642 1205 NOS from an Ebay seller, which is the old spur sprocket, for $35. I did not buy it yet.

So I can go one of 3 ways:
1. Just buy the NOS spur sprocket and be back in business, but still facing obsolete parts supply.
2. Buy the Baileys parts, and wait around for an 1104 cover to show up on the Bay
3. Or option 3: get Baileys parts, and hand modify my old 1102 chain brake cover to clear the new clutch drum, and then keep on the lookout for an 1104 cover when one comes up

The cover modification wouldn't be hard, but it would be ugly. And it would not have the stiffening rib anymore that goes around the circumference of the hole. But I doubt that will hurt anything.

Opinions please.