Chainsaw troubleshooting - rc car like sound

[wakeboarder3780]

I was cutting wood this last weekend with my dad when his saw started acting up. It had a sound like the bar wasn't getting oiled. When he revved it, it almost sounded like an rc car with this high pitched whine coming from the bar. Since it sounded like the bar wasn't getting oil from the saw, we dumped some bar oil all over the bar and let it get onto the chain - still same sounds.

My dad said he heard from friends that this is what it sounds like when the bar wears out.

Well we went and bought a brand new 20'' bar and it wasn't the problem we were still getting the same issue.

After this we started poking around and my dad noticed that the sprocket looked a little worn. I never got to see one brand new myself so I had to go on what he said.

Does this sound like it could be a worn sprocket? The only behavior besides the noise that supports this theory is eventually after revving it and cutting a few logs the chain would get insanely tight. To me if it were the sprocket this could be because the chain tooth slipped up on the gear tooth instead of staying seated in the valleys of the teeth on the sprocket.

Input?

 

[Jacob J.]

If the saw was oiling ok, and the chain was getting tight- there's usually two reasons. 1.- very, very worn sprocket or clutch drum (if the saw is equipped with the rim and drum system.) 2.- running the wrong pitch chain and sprocket combo (i.e. trying to run 3/8ths pitch chain on a .325" sprocket or something similar.)

I've never heard of a worn bar causing a chain to get tight. A bar with pinched rails will do that but the chain would be tight all the time.

 

[cord arrow]

I fought this kind of sound in a small bore Husky for a long time....

Turns out it was the washer that rests against the inner plate, behind the clutch drum. Debris had found it's way behind the plate and bowed it out...both it and the washer were quite blue...that was my key.

No way this could lead to a chain tightening, however....just annoying noise.

 

[wakeboarder3780]

Alright, cool thanks for the help! I bet it was the sprocket / clutch drum.

cord arrow, I'll remember that for later if I ever hear a sound like that with no chain tightening.