Consistent Throwing of Certain Size Chain

[CaptainMauw]

Does anyone else experience issues with saws throwing certain size chains?

I have a beefed up 461 that just does not like 28” loops. Running standard STIHL RS full-comp on both standard ES and ES-lite bars with rakers ground to .040. Chain is always tensioned proper once warmed up and monitored throughout use and it never gets loose. Despite this, the 461 throws the chain 60% of the time despite no apparent reason. Its not getting pinched/wedged/or pulled. It does it whether limbing or bucking.

The same saw will pull 32” full-comp and 36” full-comp and skip loops on both ES and ES-lite bars all day without hiccup. At this point I almost exclusively stick to my 32" setup as Im tired of fixing damaged drive links on the 28" loops. I never thought much on it until a neighbor mentioned that his 660 and 460 didn’t like 28” loops and proceeded to explain the exact same things that happen to me.

So now I am curious as to what would cause a saw to act this way. Any guesses? All saws are well maintained with relatively low hours on them. Bars are basically new with very few hours on them. My 461 probably has 150hrs ballpark since purchased new and woods ported. His saws are stock with less then 300hrs on them with standard raker depth. Curious if anyone else has experienced similar.

 

[Bob_w]

Are there bad bar shapes that throw chain easier? Just asking. I want to know too.

Does the bar set on the studs right? Manufacturing defect or damage? Sounds like the bar is the common denominator.

 

[Syflan]

My guess would be that the 28" bar has a resonant frequency that is at or near a vibration caused by the engine. I would try testing this by tuning the carb to adjust the engine speed either up or down a bit and see if it still throws the chain.
Or possibly you could attach a weight to the bar to change any resonances...
Anyway, an interesting problem.

 

[NSEric]

Im guessing when you run the 28 you're cutting with the middle of the bar more often where the chain is the slackest and easiest to throw.

 

[Tony Mayhew]

I was taught by a very smart ol boy that the farther out that you adjust the chain tensioner because the chain was not heat cycled correctly like Oregon chain gives you instructions on the back of the package your chain comes in to do! Or i see so many guys that don't know that you need to remove the bar and chain everytime you stop to fuel your saw and clean the sawdust out of the track the chain rides in because that is how the chain gets oil! If you don't do this you create a **** load of heat with no oil getting pulled along the track by the drive links! And it doesn't take very long to destroy a new chain and bar this way! I was told to try and keep the back end of the bar as close as possible to the clutch drum, or where the tensioner pin that fits in the little hole is furthest back as possible! And as NSeric said, the longer the chain is the easier it is for it to get a little slack in the middle. So give that a try and see if it corrects your issue? And get back to us and let us know if im right about this brother?

 

[HansFranz]

you need to remove the bar and chain everytime you stop to fuel your saw and clean the sawdust out of the track the chain rides in

Wait, wut?

 

[rupedoggy]

The sprocket in the bar nose may be wrong.

 

[Lightning Performance]

Likely a nick on the inside of the bar rail. If you toss new chains off on an old bar flip the bar and try again.