Saw not cutting straight

[thecfarm]

I have no idea what to try either.
Know someone with the same saw?
Put your bar and chain on theirs. 

[DHansen]

Any saw with the same bar mount would work for testing.  I would try another new chain.

[Old Greenhorn]

Well, while we  were waiting for the pump to come in I have been thinking about this a bit. Regardless of what I feel or think I have to accept that anytime I have had this issue it has been the chain, usually from hitting dirt I can't see in the log. As much as I know it is hard to accept, maybe looking at the chain teeth carefully with a loupe might show you something. I know it's a new bar and chain, I know it doesn't make sense, but I also know this is what I have always found as my problem for curved cuts.
 Sorry, other than those thoughts, I got nuttin'.

[Old Greenhorn]

HEY! Do you have another saw you could put that chain on? If that saw cuts a curve, you got something.

[fluidpowerpro]

Unfortunately the 2 other saws I have use 3/8 pitch chain. This one is 5/16.

[TreefarmerNN]

Well, while we  were waiting for the pump to come in I have been thinking about this a bit. Regardless of what I feel or think I have to accept that anytime I have had this issue it has been the chain, usually from hitting dirt I can't see in the log. As much as I know it is hard to accept, maybe looking at the chain teeth carefully with a loupe might show you something. I know it's a new bar and chain, I know it doesn't make sense, but I also know this is what I have always found as my problem for curved cuts.
 Sorry, other than those thoughts, I got nuttin'.

The last time I had a saw cutting in a curve, I couldn't see any issue with the chain.  But I put a micrometer on the teeth and sure enough, one side was sharpened shorter than the other on most of the teeth.  It wasn't much and if it had been random I don't think there would have been a problem but since it was fairly consistent, I got a curved cut.  I use a Stihl 2 in 1 and the issue was the way I clamped the saw in a vise meant I had more pressure on the file on one side because of where I was standing relative to the bar.  Even though I couldn't see the difference, it took a couple of sharpenings to get it back cutting straight. 

[beenthere]

Haven't read (or missed it) which way the curve is happening ? From above looking at the start of the cut, does it curve down and to the left or to the right?

Okay, see a cut in a previous reply #22

[Old Greenhorn]

Just to muddy the waters a bit more as I have been thinking about this today. Lately it's been my unfortunate experience to learn that products I have bought brand new from decent manufacturers are not always as good as we expect, sometimes downright poor. 
 It might be worth checking that new bar to make sure the rail tops are even and perpendicular to the bar face. Also, that new chain may not be dead sharp on both sides out of the box. Oregon chains, when I bought them, always got a touch up filing when I first installed them. The X-cuts, so far have been great. So perhaps inspecting the bar and the chain with a fresh and cautious eye might be in order here?

 This is just a thought. This is a confounding issue to me and I would really like to see it resolved.

 Also, I looked at that photo again. I may be seeing it wrong, but it appears the cut is straight until the bar is fully into the wood, then it begins to curve. Am I seeing that right, or is it just the angle of the photo? That might be a clue, but I am grasping here. The only times I have had that problem myself I could either see chain issues, or putting a new chain on made it go away.

[fluidpowerpro]

I think I may have figured out whats going on.
As mentioned earlier, late last fall I replaced the clutch drum/drive sprocket.

Well OG, I might be experiencing just what you are describing. The new part is not equal.

I was putzing with it more today and noticed that the clutch drum/sprocket has a little play in it and is sloppy on the shaft.

I always keep my old parts and I put the old one back on. It is tight with no side play.

The ID of the new one measures .631". 
The ID of the old one measures .624".
The new needle bearing that came with the new clutch drum is also slightly bigger.

The next step is to buy another clutch drum and needle bearing.
Hopefully it will be to OEM specs.

Anyone know of a good source where I can be confident I will get an OEM part?
Its a Jonsred CS2250S.

I recall the one I bought last fall was advertised as OEM but who knows if that was true.

[Old Greenhorn]

That's pretty interesting and also a tad disturbing. The first rim sprocket and clutch drum I ordered for my 2050 was made by Tilton and was Chinese crap. I just reordered for sawzilla and I think (hope) it is not chink stuff. protec or something like that. It is on shipping now.

 Still I have a hard time thinking that this is the cause of your problem. Even if it is pulling one way or the other, the bar should get it straightened out, shouldn't it? I don't know, but I guess we will find out soon enough. I hate to be negative Nelly but I am still putting my money on the chain. Let's see what we all learn.

[fluidpowerpro]

Ya we will see....

Was just on line looking and I found one that is supposed to be an OEM part.

For reference, mine is a 7 tooth spur type, .325 pitch.

I looked up my purchase last year and it turns out it was not OEM. It was supposed to be equal to a Husky P/N 578097901.

The one I found today claims to be OEM and is also P/N 578097901.

If it turn out not being the issue, Ill end up with lots of spare parts when I'm done.....

[barbender]

I have a hard time thinking that isn't a chain issue. I've really wore some bars down, and with a hand held chainsaw they still cut straight. Mostly because there is a lot of give, so a person tends to automatically correct for any tendency to go off track. 

Things are a lot more fussy with a harvester, or firewood processor where the bar is on a solid mount. They can't crooked- the bar just hangs up if the chain doesn't cut straight. 

I'd be looking closely for sharp teeth on both sides, equal length, and equal raker height.