Chain Climbing out of Bar groove!!!

[JohnCusickjr]

So...
I'm seting up a NEW 260 pro, i.e. never run, to use with 3/8" 050. (It came from my dealer setup up for .325, and I thank everyone whose assisted me over the last month).
I got a 3/8 -7 rim, a 16" ES bar and a few chains, both RSC & RM all 60 driver.
I assembled it on Saturday, needing to buck up some small stuff in tight quarters, and as I adjusted the chain tension, while turning the chain by hand, I find that the chain is climbing out of the bar groove, as it leaves the rim sprocket. It does this about once for each complete revolution, not on the same spot of chain. I tried both chains, flipped the bar around and same issue.
I came here first as the dealer I purchased from has been taxed to his limit throughout the process.
I'm stuck...
Thanks

 

[ericjeeper]

is the sproket?

the proper size? 325 or 375? That will make it climb

 

[JohnCusickjr]

Yep. The sprocket is stamped 3/8-7t, came in a bag with part #0000 642 1231.

 

[scottr]

Yep. The sprocket is stamped 3/8-7t, came in a bag with part #0000 642 1231.

John , did you make a comparison measurement of the chain pitch and sprocket tooth pitch ? Sometimes things can be market incorrectly .

 

[JohnCusickjr]

Not yet. I was hoping this time things would be correct. AGH...
Could someone walk me through the measurment checks to do. I do have capiper and mic on hand and also have access to a toolmaker...
Thanks
John

 

[geofore]

chain climb?

Do a search, Newbie has chain questions. It may be that there is no problem other than the chain is new and not run in on the bar as yet. The chain is stiff (new), once you run it on the saw it should settle down. After you read the newbie thread you should be more or less confused about the sizes you are dealing with. You'll find the specs there.

 

[JohnCusickjr]

Hmmm...New chain needing to be broken in, Now that's something I hadn't considered.:jester: I did a search and found that I had read all that came up...
SO.
I pulled a sprocket off one of the 361's we have in service, also a 3/8 .050, and the pins line up pretty evenly. Not sure what the tolerances are on this stuff. They are not perfect.
I laid the new 16" chain out alongside a few loops of new 20" that we had on the shelf and all links line up exactly.
Stumped

 

[scottr]

John , you could measure the distance around your rim and see if the distance is the same as the chain with the same number of drive links .

 

[JohnCusickjr]

Well the OD of the 260 sprocket is EXACT as the OD of the 3/8 sprocket off of the 361.
thanks though...

 

[bwalker]

This may sound really dumb, but did you forget to replace the clutch bearing?

 

[sugarbush]

Well the OD of the 260 sprocket is EXACT as the OD of the 3/8 sprocket off of the 361.
thanks though...

check the bar sprocket to make sure its 3/8s, stand the bar on end and drape your chain over sprocket, roll back and forth, try .325 and 3/8s. one will mesh ok the other won't.

 

[JohnCusickjr]

All questions are fair game and I appreciate them.
Clutch bearing?
I have the same, is it a clutch cover? or drum?, on the saw that was there with the original .325 setup (Part # 112111602910). This cover has the smaller dia gear/spline that this new 3/8"rim sits on. The drive sprocket bearing is the original.

 

[XJWoody]

check the bar sprocket to make sure its 3/8s, stand the bar on end and drape your chain over sprocket, roll back and forth, try .325 and 3/8s. one will mesh ok the other won't.

Along that line, what is the bar part # (3003-000-????) and other info stamped on the r/s of the bar, down at the powerhead end?

 

[scottr]

All questions are fair game and I appreciate them.
Clutch bearing?
I have the same, is it a clutch cover? or drum?, on the saw that was there with the original .325 setup (Part # 112111602910). This cover has the smaller dia gear/spline that this new 3/8"rim sits on. The drive sprocket bearing is the original.

John , it is called a drum not a clutch cover . Is the drum bearing installed ?

 

[JohnCusickjr]

Bar # is 3003 000 8813, 16" ES 3/8" .050
The drum bearing IS installed. I've had the drum off, all looks ok, no loose/stray parts, Brand New...

 

[XJWoody]

Hmmm Ok that should be the right bar... now how about the chain. (Stihl chain yes?) There is a number (or numbers if not a Sth) on the drive link...

Edit: Also if there is a cup spring under the sprocket clip, make sure it's dished with the wide end in towards the sprocket

 

[scottr]

Bar # is 3003 000 8813, 16" ES 3/8" .050
The drum bearing IS installed. I've had the drum off, all looks ok, no loose/stray parts, Brand New...

Could you roll the rim on a flat surface to see if it is true ?

 

[JohnCusickjr]

Two new chains .
#1 - 33 RM 60, a #3 on the drivers, & 3/8 on the side of the cutter
#2 - 33 RSC 60 sams as above as well as a c on the side of the cutter.

Just checked the 'trueness' of the roll, and the both rim sprockets, one off of the 260 and the one from the 361 behave the same. Did notice that the driver profile on the 361 rim is flush with the OD of the piece, where as the ones on the 260 rim are a bit shy of that, I would guess a few thousandths?
There is a type of washer under the c-clip that has an open roll on one face that is oriented in to the rim.
Thanks all

 

[scottr]

Two new chains .
#1 - 33 RM 60, a #3 on the drivers, & 3/8 on the side of the cutter
#2 - 33 RSC 60 sams as above as well as a c on the side of the cutter.

Just checked the 'trueness' of the roll, and the both rim sprockets, one off of the 260 and the one from the 361 behave the same. Did notice that the driver profile on the 361 rim is flush with the OD of the piece, where as the ones on the 260 rim are a bit shy of that, I would guess a few thousandths?
There is a type of washer under the c-clip that has an open roll on one face that is oriented in to the rim.
Thanks all

My 044 has the cupped washer with the cup (concave) to the E clip . That is what makes it so fun to change .

 

[XJWoody]

Huh... that all seems to be checking OK. I dunno man?