Chain cuts well, sometimes

[billtheconqueror]

Someone gave me an older Stihl 025. I replaced the carb on it, fuel filter, air filter and it is running well.

I sharpened the chain (I am still learning to do this, but I've done it "successfully" with a couple other saws I have) (by "successfully" I mean that it cut much better afterwards than before I sharpened them. In other words, I'm a newbie).

When I tested the Stihl 025 on a couple logs I have in the yard, it would cut well (and pull itself into the log) sometimes, but occasionally (3 or 4 time on a 10-inch diameter log) it would seem to not cut at all or very little, like it was just going to try to burn through. Then it would pick up again and cut well. Does anybody know what this might point to?

Thanks for any advice!

 

[esean]

Any change in how the motor's running when this happens? Could throw a new chain on and see what that does. Might help if you post close up pics of the chain in question.

 

[Bubster]

Check the sprocket and also file the burrs off each side of the bar.

 

[Big_Eddy]

Sounds like the bar rails need truing or the bar slot is too wide / needs to be closed up. The chain runs true sometimes, and other times it tilts and then does not bite properly.

 

[billtheconqueror]

Any change in how the motor's running when this happens? Could throw a new chain on and see what that does. Might help if you post close up pics of the chain in question.

Here are a couple close-ups. I didn't notice the engine running any different during those times.

 

[billtheconqueror]

Thanks for the ideas everyone!

 

[SteveSr]

Here are a couple close-ups. I didn't notice the engine running any different during those times.

That bar needs to be, at least, dressed. I suspect that it is worn out. clean up the bar and get out your feeler gauges to measure the width of the slot and compare it to the gauge on the bar. An .063" gauge bar slot should measure about .065" when new. The other thing to look at is how "floppy" the chain is side to side.

It looks like the P.O. didn't have a clue to sharpen the chain and ruined the bar and likely the sprocket. Put up a photo of the sprocket.

 

[PV Hiker]

Your depth gauges are all over the place for height. Some are filed and some are not. Set all the depth gauges for the cutters.

 

[pioneerguy600]

It looks like the depth gauges have been hammered, not filed and the cutters are not sharp or consistent, put the pic under the highest magnification and it is easy to see the chain condition and then the bar is in very rough shape as well, needs dressed and inspected as already mentioned.

 

[Okie]

Ronnie Milsap can see that chain is not correct.

You at least need a new chain.
Post up a picture of your sprocket. If it's worn at all replace it or a bad sprocket will ruin a new chain.
When you get the chain off the bar do as the previous guys suggest about inspecting the bar.

 

[Big_Eddy]

That chain is going to come apart soon anyway. Too much file damage on the links.
And you clearly need a new drive sprocket. It is chewing up the underside of the links.

 

[Husky77]

Here are a couple close-ups. I didn't notice the engine running any different during those times.

Luke PV said below, itsbyour rakers. I just looked close up and they are all over the place, get yourself a gauge and learn to use it properly. Most people think you just grab a chain saw and it cuts, they never learn how to use and look after it, there is much more to it and your more likely to get hurt with a blunt chain or a saw that dont run right. Wear proper PPE and keep it sharp. Good luck

 

[Timber MacFallen]

I'd start with a fresh chain myself- I wouldn't even want to salvage that beat up chain myself unless I had no choice. I bet the drive sprocket is in rough shape and the bar needs serious work too.

It probably led a tough life. If the saw seems in good shape though otherwise maybe a fresh bar and chain is in order. I have a feeling that bar has suffered a lot of unnecessary wear from a tweaked chain.

 

[Philbert]

Here are a couple close-ups

Your chain is blurry! That’s the problem!

Seriously, if the cutters are filed unevenly, Right and Left (length, angles, etc.); or, if your depth gauges are not set properly; or, if your bar rails are uneven (or, any combination of the above) . . . .

. . . your chain will try to cut more on one side, cutting a curve, instead of a straight kerf.

This curve may be subtle, but too tight for the guide bar to follow, so it hangs up. Typically, this happens 3” to 4” in.

Chains and bars can often be cleaned up, but that chain is pretty far gone. I’d second @Timber MacFallen’s advice, and go with a fresh chain, for your ‘new’ saw.

Philbert

 

[SteveSr]

Thanks for the ideas everyone!

I see a new bar chain and sprocket in your future.

Now would be an excellent time to replace it all with a 3/8" LP setup (Stihl Picco) like the 025s smaller siblings had. It will really increase the cutting performance. Stihl also has a rim sprocket conversion kit for this saw which would also be a good investment.