Problem with Chain Flying Off Bar & Sproket -- STIHL 025

[Vernon Tull]

Gentlemen -- Here in Alabama we had a lot of trees down due to the pounding we took last week with Hurricane Katrina. I spent several hours Saturday working with my 025 to try to clear out some of our ATV trails. My dilemma is this: when I use the green-link, low-kickback chain, I have no problem except for getting a slower, less agressive cut, but when I put on the yellow-link, so-called "full chisel" chain, my saw cuts great for a for a minute and then slings the chain off the bar and sprocket. And yes, I have looked carefully at the chain's model number to see that it is the right one for an 025 sprocket and bar. I should add that my sprocket is not worn much at all either. Any ideas?

 

[tony marks]

ok ,something is different. what it is, only u can discover. i suggest u look into the possibility that u are using chain not specifically made for stihl saws . the power match equipment ive used ,really is amazingly different. so dont assume what the package says necessarily is really rite. stihl sizes are a little different. dont ask me why. good luck.

 

[HiOctane]

Maybe your full chisel is one or two links longer putting sprocket and blade farther one to the other allowing the chain to fall more easily.

 

[NWCS]

is it possible your using 3/8" chain on a .325 sprocket and bar tip? or another similar situation mismatch? a few Stihl dealers in my town are well known for selling the wrong parts every time, could be the same deal.

like the time i ordered an 084 carb rebuild kit and got an 044 kit.. theres a major size diffrence there.. they swore up and down it was the proper kit too..

 

[Lawn Masters]

Maybe the wrong gauge chain? its possible I think, and is it tensioned properly?

 

[pallis]

I had the same problem yesterday. As it turned out, I had put a .063 bar on thinking it was a .058. A quick bar change solved the problem.

 

[ray benson]

What are the numbers on the chains, also number of drive links on the chains and the bar numbers?

 

[lostone]

How are all of the drive links,have you checked them for any damage? What kind of sprocket do you have and what kind of shape is it in? when the "Full chiesel chain" in on the bar can you adjust it to where it needs to be and still be able to move the chain freely around the bar?

 

[G-MAN]

your probably cutting very small diameter stuff. if you aren't cutting full speed through it with the full chisel chain it will grab the wood and pull it off. so try cutting at wide open throttle and you should be cured.

 

[Vernon Tull]

Thanks, fellows, for your ideas. After reading all of your suggestions I double checked all the specs for the suspect chain and the bar/sprocket combo on my 025. The chain is a genuine Stihl 18", 26RS-68, Pitch .325, Gauge .063, Drive Link 68 just as the bar and sprocket require and a perfect match to my less aggressive "Green Link" 26RM2-68 that gives great, smooth service.

Of all your good suggestions, G-MAN's may be a factor since some of what I was cutting was smaller in diameter. However, upon very close inspection, I did find that one of the suspect chain's links is "sticky" or stiff at one of the pivot points -- that is, it doesn't flex quite like the others; it's like that link is slightly pinched or binding. I've put it on the bar with the chain cover off and slowly moved it around its rotation on the sprocket. Generally that link moves around the sprocket fine, but maybe at high engine speed a problem can show up that I wouldn't see at slow hand speed. The chain is one I bought quite a while back and have used only occasionally, so it is not old in terms of actual use. I suppose, though, that any product can show abnormalities or flaws . . . even genuine Stihl parts.

 

[buck futter]

If the small stuff is the problem you can run your chain just a little bit tighter than normal. Also did you soak the chain in oil overnight or longer?

Best wishes
Lucky

 

[kf_tree]

If the small stuff is the problem you can run your chain just a little bit tighter than normal. Also did you soak the chain in oil overnight or longer?

Best wishes
Lucky

i have to bite on this.........what does soaking the chain in oil do?

 

[Lawn Masters]

soaking a chain in oil, basically helps to lubricate it better, which sometimes,frees up stuck or stiff links and gets things going again.

 

[eric_271]

If the chain tension is too loose and you put the bar in a little bind it will throw the chain. You may know this and then maybe not but once you start your cut you need to go straight through the wood, dont try to change the angle of the cut once the bar is in the wood. Is your chain sagging any on the bottom of the bar befor you make the cuts that throws the chain?

 

[Vernon Tull]

Eric -- No, I don't let the chain sag any on the underside of the bar. I go with what I think my owner's manual said . . . something like no sag at the bottom and tight enough so that when I pull the chain up on the top side of the bar, I can see about three drive teeth. That non-precise setting has worked well with all the other chains and saws I've used over the years.

My kinfolk around here tell me that I should set the chain tension so that it sags a little at the bottom of the bar, but my Stihl owner's manual doesn't say that so I don't. I keep the chain a little tighter than the kinfolk do on their saws, but not overly tight or binding.

 

[Fish]

Soaking it in oil has reinvigorated my marriage again, but it still sags a little at the
bottom. It has got things going again at least, thank God for Synthetic oil!

 

[eric_271]

Fish go cialis if you want to get the sag out of the bottom. You may gain some rpms as well.

 

[SawTroll]

No sag - No drag !

 

[Lobo]

Fish go cialis if you want to get the sag out of the bottom. You may gain some rpms as well.

Cialis or not, all bottoms with time sag.

Fish face up to it, you have far more behind you, than what is left ahead of you.

 

[eric_271]

Mine sags after I have run it hot. I found that if I add 10mg of cialis to the fuel tank and shake it around it gets tight again. Is this normal?