Dimished performance

[Adamj]

I took my new Stihl 660 for a test drive on some 14-24" oak last week.  It sawed like an animal for the first 25 cuts (1 hour).  After the first hour, I noticed that the saw was having much greater difficulty cutting the same wood.  Several days later I returned to the wood pile and repeated the same cutting pattern.  Once again, after one hour the saw cutting performance dimished severely.  Thus, I broke out the Stihl 029 to finish the job (the 029 felt like a had just left a Porsche in favor of a Yugo).  On both occasions, the saw seemed to be running fine and the chain had visible oil in the grove of the bar?  Please help me understand what is happening.  

[Gus]

Is the chain binding ? Check the clutch for heat, also the bar and chain.
Gus

[Kevin]

I might be missing something here but it sounds like a dull chain.
Most guys will sharpen after every one or two fuel fills.

[Bro. Noble]

DanG,  I read the title "Diminished performance" and said to myself  now here's something I know about and then I find you guys talking about chainsaws

[SasquatchMan]

Is it possible that you're into a denser portion of tree after an hour of cutting?  I notice when I'm sawing that certain pieces of wood cut like butter and others make me wonder if the chain even has teeth...  I also wonder if a delayed problem like that could be mix related somehow... but you would sort of think if the engine was gunked up it would stay gunked up cold too...

[Adamj]

Kevin,

I would have thought the chain was dull also.  However, when I returned the next day, the saw cut like a banshee.  It wasn't until one hour later that the saw began to cut poorly.  The next day brought then same results: great cutting for the first hour and fair cutting after that.  I have two tankfulls in the saw and have not sharpened the blade yet.  

As far as the wood difficulty increasing, I bucked several large tree sections, from a variety of tree's during that time.  I returned the next day to satisfactorily tackle the prior days sawing difficulty.  I am perplexed.  

[SasquatchMan]

  well that figures... gotta hate it when your saw has a problem that a two-stoke engine should be too simple to have...  I noticed a post by typhoon mentioning that a new chain seemed to be binding up after use, so I wonder if you have a situation like that, where the thing comes up to temp and gets a bit sticky, robbing you of power?

[Kevin]

If the chain becomes hot it will get loose on the bar and if you tensioned it while it was hot and it had a chance to cool it would become very tight causing drag.
Do the wood chips look the same before and after this occurs?
Does the engine sound any different when this happens?
Is everything clean and free of sawdust?

[Adamj]

Kevin and Sasquatch,

The saw was brand new and had not been used prior to the first hour, for which I subsequently experienced problems.  I assume that the dealer tightened the chain while the saw was cold.  I have not made any adjustments to chain or saw since purchasing it from the dealer.

The engine has performed consistently and gives no obvious sign of trouble or fatigue.  I had fresh premium fuel (1hour from purchase and using 50:1 Stihl oil along with full tank of Stihl bar oil). The best way to describe the performance difficulties would be similar to a dull chain.  However, the next day the same chain and saw did great for an hour without any problems, until the problems started again.  It almost seems that the chain is getting hot and does not want to cut.  HELP !!!!!!!  

[Kevin]

If the chain hasn't been sharpened it needs it.
If you run the saw with the tip of the bar close to a stump or something else you should see oil spray on the surface.
You might have to crank up the bar lube out-put... or clean the bar.
It's difficult to diagnose something like this without seeing it, if you can't resolve it don't hesitate in getting help from your dealer.

[SawInIt CA]

an hour is about enough cutting any way

[Gus]

I agree with Kevin. Take it back to the dealer and have him take a look see. It probably needs touched up a bit. (the chain).After every tank I give the chain a quick whirl to see what it looks like. You don't even need to look at the cutting edge per-se just look to see if there is the beginning of buildup on the top of the teeth.  Build up is caused by pitch warming up and collecting on dull teeth from the heat.
Let us know what it amounts too OK?
Gus

[Oregon_Rob]

I agree, go to the dealer. He made good money off the sale and part of that money is for customer support. Don't be shy about asking questions, it's his job to keep you happy.

[Adamj]

Thanks Gentlemen.  I will take the saw back this weekend and see what the dealer has to say.  I will have the chain sharpened at that time.  Unfortunately, I have little confidence in this dealer.  They are a moderately sized farm supply dealer that deals primarily with farmers, not logging folks.  I did not sense a great deal of expertise from them.  To give you some idea, they marveled at the Stihl 660.  They told me that they have sold only 1 or 2 088's and a few 066's.  We'll see what they have to say.  I will keep y'all updated.