# The chain is already spinning...



## 1750 (Jun 8, 2014)

I cut all day with my little Stihl MS-170 yesterday.  That saw is a trooper!

 Sometimes I noticed that when I started it up, the chain would start spinning as soon as I took  the brake off and before giving it the gas.   Similarly, after finishing a cut sometimes it keeps spinning (and fast) even when I'm not pulling the trigger.

I've taken it apart and cleaned everything up.  It doesn't seem to be a sticky trigger assembly, because it happens even before it's been given the gas.   It doesn't happen even most of the time, but I'd like it to happen none of the time as I could see it creating a dangerous situation.

If anyone is familiar with this problem and has suggestions for fixing it, I'd appreciate your input.

Thanks!


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## TreePointer (Jun 8, 2014)

Just to cover all bases, are you familiar with Stihl startup procedure?  The "Warm Idle" position is actually a "fast idle," which will cause the chain to spin rapidly.

Chain spinning at idle could mean the idle setting (LA) on the carburetor is too high.  However, this usually is a little movement and not spinning rapidly.

Clutch springs may need to be replaced.


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## 1750 (Jun 8, 2014)

Yes, I'm familiar with the start-up procedure.  Although, now that I think of it, the saw stopped doing it as much after I'd been cutting for a while and could just start from the first position.   I've got a bit more to do today to finish up.  I'll go pay better attention to where the control lever is.   

When I start I typically have the brake on.   After it's up and running, I drop the brake and that's when it starts spinning.

Regardless, thanks for your reply.   I'll go pay a little better attention to what's going on.


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## bobdog2o02 (Jun 8, 2014)

could be lean on the idle screw too


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## 1750 (Jun 8, 2014)

Thanks, Bob.

I just went out and finished cutting up the smaller stuff.   There wasn't any problem today, so maybe it was just me messing something up.

Thanks again.


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## Highbeam (Jun 9, 2014)

My 290 did that almost since it was new. It was my first Stihl so I just got used to it. I tried tightening the chain and lowering the idle speed to get it to stop.  

It finally drove me nuts so after removing the sidecover, bar, and chain, I popped off that e-clip and pulled the sprocket/clutch drum off. This is all really easy. I was happy to find that one of the clutch springs was broken. Replaced the pair of springs for super cheap and put it back together. Totally different saw.

It's not a pro model but when the chain is sharp, that saw can make some firewood fast.


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## jeffesonm (Jun 9, 2014)

Does it have the auto-tune carb?  My 180 does and it also spins occasionally, but just as its getting warmed up.  Once it's warm there's no problem.


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## 1750 (Jun 9, 2014)

Highbeam said:


> My 290 did that almost since it was new. It was my first Stihl so I just got used to it. I tried tightening the chain and lowering the idle speed to get it to stop.
> 
> It finally drove me nuts so after removing the sidecover, bar, and chain, I popped off that e-clip and pulled the sprocket/clutch drum off. This is all really easy. I was happy to find that one of the clutch springs was broken. Replaced the pair of springs for super cheap and put it back together. Totally different saw.
> 
> It's not a pro model but when the chain is sharp, that saw can make some firewood fast.



Thanks, HB.  The problem is variable, so I don't think anything is broken -- sticky, maybe, but not broken.

This saw has a lot of heart.  It's a 16" bar working through 18" of sugar maple all day long.    I had never had it do anything but smaller diameter stuff, and was impressed with what it could do.

Thanks for your reply.


jeffesonm said:


> Does it have the auto-tune carb?  My 180 does and it also spins occasionally, but just as its getting warmed up.  Once it's warm there's no problem.


Jeff, I don't know if it has an auto-tune carb.   Your description fits what I experienced, though.   As soon as it was warmed up things seemed to be fine.  I'm cutting against next weekend, so we'll see if the pattern repeats.

Thanks to you both.


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## bobdog2o02 (Jun 9, 2014)

This is an intellicarb model.....


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## 1750 (Jun 9, 2014)

Intellicarb sounds like something from Star Trek, Bob.   

I could only hope to have an Intellicarb!


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## bobdog2o02 (Jun 9, 2014)

1750 said:


> Intellicarb sounds like something from Star Trek, Bob.
> 
> I could only hope to have an Intellicarb!



Check out the features tab........  seems a whole lot like an auto tune to me......

http://www.stihlusa.com/products/chain-saws/homeowner-saws/ms170/


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## 1750 (Jun 9, 2014)

bobdog2o02 said:


> Check out the features tab........  seems a whole lot like an auto tune to me......
> 
> http://www.stihlusa.com/products/chain-saws/homeowner-saws/ms170/


This is great, Bob.   This saw is about 10 years old, but it sure looks like that picture.

Thanks for the great link.


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## bobdog2o02 (Jun 9, 2014)

Well you didnt say how old it was........   Check your filter and low speed fuel screw, as long as your clutch is functioning properly.  A hole in your filter can cause this too


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## 1750 (Jun 9, 2014)

Thanks, Bob.  I don't actually know how old it is.  It came out of someone's garage as part of an estate.

I've got a pdf of the manual, I'll have to take a closer look.

Thanks!


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## Bigg_Redd (Jun 10, 2014)

1750 said:


> If anyone is familiar with this problem and has suggestions for fixing it, I'd appreciate your input.




How about leaving the break on, eh?


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## D8Chumley (Jun 13, 2014)

I love the heck out of my 170, that is the saw I use most. Like a Timex...


Bigg_Redd said:


> How about leaving the break on, eh?


Good point BiggRedd


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## bobdog2o02 (Jun 13, 2014)

Bigg_Redd said:


> How about leaving the break on, eh?


great idea, mask the problem.  Orrrrrrr, make it idle right.


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## Bigg_Redd (Jun 14, 2014)

bobdog2o02 said:


> great idea, mask the problem.  Orrrrrrr, make it idle right.




Engaging the chain brake while not actively cutting is standard practice recommended by every entity that promotes chainsaw safety. I don't do it but it is the standard.


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## Jon1270 (Jun 14, 2014)

Bigg_Redd said:


> Engaging the chain brake while not actively cutting is standard practice recommended by every entity that promotes chainsaw safety. I don't do it but it is the standard.



Yep, I took a Game of Logging workshop this past Spring and two of the safety violations for which they deduct points are starting the saw or taking more than 2 steps with the brake disengaged.


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## bobdog2o02 (Jun 14, 2014)

I don't argue those points but every saw manual I have seen states that at idle the chain should not turning,.......


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## TreePointer (Jun 14, 2014)

Engaging chain break between cuts or while walking prevents incidents resulting from inadvertently hitting the throttle trigger.  The problem presented in this discussion has the chain moving without hitting the throttle trigger.  If chain is moving at idle, something needs to be corrected.


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## Bigg_Redd (Jun 14, 2014)

bobdog2o02 said:


> I don't argue those points but every saw manual I have seen states that at idle the chain should not turning,.......



But if you're operating the saw safely how would you know?


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## bobdog2o02 (Jun 14, 2014)

When you take the chain brake off are you pulling the throttle at the same time?  .....  Really?


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## Highbeam (Jun 14, 2014)

I think it's a stupid rule that the chain brake ever be engaged as a matter of SOP. The chain should not spin at idle regardless of the existence of a chain brake.


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## maple1 (Jun 15, 2014)

I never use my brake.

If your saw is working right, the chain won't be turning when you're not pulling the trigger, and you can't pull the trigger without your hand fully around the trigger handle to first push down the trigger release thingy.


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## Jon1270 (Jun 15, 2014)

maple1 said:


> If your saw is working right, the chain won't be turning when you're not pulling the trigger



...unless the fast idle is engaged, as it often will be when starting a saw.



maple1 said:


> ...and you can't pull the trigger without your hand fully around the trigger handle to first push down the trigger release thingy.



...which helps, but doesn't absolutely prevent accidentally grabbing the throttle at an unfortunate moment.  Chainsaw users do tend to grip that rear handle now and then, even when they aren't actively cutting.

Obviously the OP needs to get their saw fixed, but a little redundancy in safety measures is a good idea.  Locking the brake is sort of like flossing your teeth, i.e. a habit that's hard to establish because it's not any fun, with benefits you never tangibly see no matter how statistically, demonstrably real they are.


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## Bigg_Redd (Jun 15, 2014)

Highbeam said:


> I think it's a stupid rule that the chain brake ever be engaged as a matter of SOP.



Agreed



Highbeam said:


> The chain should not spin at idle regardless of the existence of a chain brake.




Also agreed.  I'm just being an @$$.


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## bobdog2o02 (Jun 15, 2014)

Bigg_Redd said:


> Agreed
> 
> 
> 
> ...


sometimes its hard to tell.....


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## maple1 (Jun 15, 2014)

Jon1270 said:


> ...unless the fast idle is engaged, as it often will be when starting a saw.
> 
> 
> 
> ...


 

All true, yes. Only relating what I have always done. Maybe it could be called bad habits - but everything I have ever done with a saw swings on utmost respect for the trigger. Some might argue that respect might diminish a bit, maybe, with constant reliance on the brake - but I won't.


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## kevin j (Jun 16, 2014)

Need to define a fork in the road: rpm or mechanical. 

Is the engine idling faster then normal? Then find out cause of higher idle that engages clutch. Adjust carb or air leaks or switch in correct low idle position. 

If idle rpm is normal, then mechanical problem in clutch. Grease bearing and check or replace springs. 

Son's 180 was very nice fast lightweight saw. 

K


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## Highbeam (Jun 17, 2014)

I just took apart the MS290's clutch last night to clean the drum and grease the bearing, check the springs. All those springs being in place and clean is pretty important.


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## Hogwildz (Jun 17, 2014)

My 361 does this occasionally when the chain gets loose and needs adjustment.
After adjustment, all is well.


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## TMonter (Jun 19, 2014)

Hogwildz said:


> My 361 does this occasionally when the chain gets loose and needs adjustment.
> After adjustment, all is well.



As Highbeam said check the needle bearing on the clutch. If the bearing gets dry it can stick and cause this condition. Put a little high temp grease on the bearing and re-assemble it.

All my saws seem to need this every few years so I've just gotten in the habit of doing it once a season before I put the saw up for the winter.


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## Highbeam (Jun 19, 2014)

TMonter said:


> As Highbeam said check the needle bearing on the clutch. If the bearing gets dry it can stick and cause this condition. Put a little high temp grease on the bearing and re-assemble it.
> 
> All my saws seem to need this every few years so I've just gotten in the habit of doing it once a season before I put the saw up for the winter.




It's been bugging me and since the photo above shows it very well, there are indeed three springs and not just two as I mentioned earlier. If needed, replace them all at once.


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## Mischa Shashumshkavich (Jun 26, 2014)

i was watching a television show called ''AX-MEN'', and one kid after felling a pretty large pine, stepped back and up onto  the stump end of a tree already felled, when the falling tree landed it hit the tree he was standing on and sent him head over toe while holding the saw, and squeezing the trigger....when he landed on his butt the bar landed on his leg then he tried pushing it away with his hand.....he stood up and asked the cameraman, '' you didn't get that did you''........VERY lucky not get cut......not wearing any eye or neck protection and not using the chain brake with those monster saws in those kind of cutting conditions is pretty,,,,,risky


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## clemsonfor (Jun 29, 2014)

Tighten your chain. Once tight learn the correct finding method. Probably a combination of idle speed and L adjustment.??


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## clemsonfor (Jun 29, 2014)

Or an air leak if this saw has some hours on it?


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