Sproket question

[pallis]

Sprocket question

I have a Poulan Pro 295 that gets used for limbing, and cutting firewood. I put a 3/8 rim sprocket on it when I first bought it. Today, I decided to go with a .325 7 tooth sprocket. When I put the chain on, it turns smoothly for about three quarters of the way around the bar and then binds a little. I tried it with an 8 tooth sprocket, and the chain turns smoothly with no binding. I also tried a couple of different bars and chains, same results. Does anyone know what is causing this? It's not the same thing as putting a .325 chain on a 3/8s sprocket, or the other way around. It turns smoothly, binds, and then turns smoothly again.

 

[Crofter]

You cannot use both .325 and 3/8 chain on the same sprocket nose bar. Also a chain that is worn and elongated in pitch can work smoothly on its matching worn sprocket, but put that chain on an unworn sprocket and it clashes.

 

[pallis]

The chains and sprocket are matched, .325. The chain and 8 tooth sprocket came off a Jonsered 525, so they might be worn equally. The problem is that I tried it with a different bar and several chains and got the same results. Maybe the 7 tooth sprocket is faulty. I took it off an old Dolmar. Next time I'm in town I'll pick up a new one and try it. Until then, the 8 tooth will have to do. Thanks! Pat

 

[Crofter]

"I put a 3/8 rim sprocket on it when I first bought it. Today, I decided to go with a .325 7 tooth sprocket."

If the above is correct and it is a sprocket nose bar, something does not add up. What am I missing?

 

[rmihalek]

Your best bet is a total swap: new sprocket, new chain, new bar. My guess is the problem would disappear. Mixing old parts with new ones it like the "weak link in the chain" analogy. You're pulling the performance level of the new parts down to the level of the old parts.

 

[pallis]

"I put a 3/8 rim sprocket on it when I first bought it. Today, I decided to go with a .325 7 tooth sprocket."
"If the above is correct and it is a sprocket nose bar, something does not add up. What am I missing?"

Don't worry Frank, I excel at confusing people.. I also changed to a .325 bar and chain. I think the worn sprocket suggestion is right. The 7 tooth sprocket came off an old Dolmar that my son used. I think he might have tried running a 3/8s chain on it, or something. Anyhow, the .325 8 tooth sprocket is about the same diameter as the 7 tooth 3/8 that I was using. I'll take the squirrel's advice and run with it. I was just curious about why .325 sprockets of different sizes didn't both work correctly.

Thanks!
Pat