# MS660 tuning for milling



## JELIII (Dec 3, 2009)

I have a relatively new MS 660 that I was planing to put on a 48" Alaskan. What do I specifically need to do to try and prevent damaging the saw. I realize after reading a number of posts here and on other sites that I should probably start looking for a larger saw for this size mill, but I have both at this point and would like to try and make the most of what I have. In particular I am not sure I completely understand the carb adjustment instructions in the manual and based on what I have read I want to make sure I have it set a bit rich. I have read the procedures desired in Malloff, but I am nervous to even try to adjust it until I am clear on which way I should be turning the high jet. The manual talks about going 3/4 of a turn for the initnal setting, but the screw only has 3/4 of a rotation of total travel. Should I be modifying the muffler? This forum is a great help to all us newbies! Thanks for sharing the knowledge


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## mtngun (Dec 3, 2009)

To richen the high, turn the jet out (counter clockwise).

To lean the high, turn the jet in (clockwise).

Sounds like your carb has limiter caps. You might want to pull them, cut off the limiting tab, and then reinstall them sans tab. Often they are destroyed in the process of removing them, so it may be just as well to buy replacement limit caps from the dealer.

Assuming you have the newer style muffler with one solitary exit hole, then yes, I'd suggest enlarging that one exit hole (while retaining the spark screen) and also drilling a couple of holes in the inner cage. 

It takes a while to learn to tune a saw by ear. Madsen's has a good tutorial. saw tuning

I've been trying to tune by ear for several years, and I'm getting better at it (I'm somewhat tone deaf) but sometimes I still don't trust my ears, especially on a saw with an effective muffler. A tach provides a nice sanity check for us tone deaf types.


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## woodsrunner (Dec 3, 2009)

JELIII said:


> I have a relatively new MS 660 that I was planing to put on a 48" Alaskan. What do I specifically need to do to try and prevent damaging the saw. I realize after reading a number of posts here and on other sites that I should probably start looking for a larger saw for this size mill, but I have both at this point and would like to try and make the most of what I have.



I would not be worried about a bigger saw just yet. Your mill will adjust "down" to a smaller bar. I run a Husky 395 with a 42 inch bar with no problems. I think you will be fine with the 660. Especially since you are just getting started. Learn and get accustomed to the whole process with what you have and then you will know better how to proceed to the next level.
BTW welcome to the crazy world of CSMing!

Scott


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## ShoerFast (Dec 3, 2009)

Mof-mod it, trim off the tabs of the limiter caps run it fat-rich, counter-clockwise, very possible slightly over a full turn out but don't go by amount of turns, that's just a reference. 

Muf-modding will allow it to run cooler, as well as a slightly fat carb setting. 

Keep your chain sharp and don't crowd-force feed it much, let the chain do the work. 

Going from a good tan color plug to more of a coco-color is fine for longevity. 

In the long run....
_
It's better the plug, then the jug!_​


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## excess650 (Dec 3, 2009)

I would suggest the dual port muffler, fuel/oil mixture at 40-1, and tuning for 11,000K max rpm. 

My own milling saw (066)has a Bailey's big bore kit:spam: and definitely has more grunt:chainsawguy: than my "higher than stock compression" 660.

Tuned and fueled as suggested, I've milled in 90*F temperatures without engine issues. The clutch has taken a beating, but its a wear part.opcorn:


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## JELIII (Dec 3, 2009)

Can someone give me more details on what I need to do t to the muffler, or am I better off spending the 120 on a dual port? 

I will remove the tabs you are describing from the carb adjustments tomorrow.

Thanks for all the advice.


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## BIG JAKE (Dec 3, 2009)

JELIII said:


> Can someone give me more details on what I need to do t to the muffler, or am I better off spending the 120 on a dual port?
> 
> I will remove the tabs you are describing from the carb adjustments tomorrow.
> 
> Thanks for all the advice.



Just get the dual port cover it's all you need(not the whole muffler). Should be around 50 bucks. Also, the max bar you can run on your 48 is probably a 42" bar. The 660 should pull that just fine. Let it eat the wood it wants though. Yes, pull the limiter caps I would not mill with those in there. Then again, at your elevation you might be ok. Don't scrimp on oil either. Stihl, Husky, Klotz, Maxima 427, etc. 40:1 with premium gas.


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## JELIII (Dec 4, 2009)

I bought the whole mill set up with a double ended bar with a roller in the helper handle - I think the bar is 48", with an oiler at the other end. I am just starting to put it together. I hope this wasn't a bad choice of bars.


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## Andrew96 (Dec 4, 2009)

Well this is up my alley. I too have a quite new MS660...stock right now. So you guys would agree the hot setup is:
40:1 (not 50:1) Premium gas, premium oil, I don't intend on starting another oil ratio argument.
Muffler mod, either dual port cover, or DIY fabrication.
Of course, Pull the caps and run it a bit rich. 11,000rpm max.
Aux oiler for bars 36" or longer. 
Let the saw eat the wood by not forcing it to cut. 

So...anything else? I was hesitant to get a dual port cover as I didn't want it to be too loud. Therefore I haven't pulled the caps as I'm rich enough within the limiter caps range. 
From the parts list I can see a high compression base gasket (thinner for higher elevations). Is this how you guys got a 'high compression' engine?
My big concern with any mods was reducing the lifespan on the saw. Hence..no muffler mod. Is this the correct assumption?


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## BobL (Dec 4, 2009)

Andrew96 said:


> .
> .
> .
> .
> ...



from someone who seems to know his stuff.


timberwolf said:


> There are gains that can be had by porting a saw for milling, However the standard approach of just increasing the port durrations *and bumping compression might not be the best though.*
> 
> A milling saw needs torque more than it needs RPM, ported for more torque and the saw will hold more RPM in a heavy cut and cut faster. *If compression is increased much over stock heat will be a problem on a CSM.*


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## mtngun (Dec 4, 2009)

The dual port is controversial. I vote "NO."  It's very NOISY, overpriced, did not increase power compared to a modified single port, and worst of all, blows hot exhaust on my hands to the point that it's difficult to hold the mill, even with gloves on.

I don't have a single port muffler to show you, but it is easily modified to give satisfactory results. The factory outlet hole is about 1/2", use a dremel or die grinder to open it up to at least 3/4". Watch that the enlarged opening does not bypass the spark screen.

There is a cage inside the muffler that has a few holes in it. The cage is restrictive compared to older 066 mufflers, so drill a few more holes in the cage, or enlarge the existing holes.

Before you can jump to any conclusions about compression, measure the compression you have now. If it is 160 or better, then you are good. If it is below 140, then measure the squish, and depending on what you find, you might consider pulling the factory base gasket and reinstalling the cylinder to have 0.020" squish. 

Engines produce heat, fact of life. The whole operating principle is based on heating air. The hotter the air gets, and the more air moves through the engine, the more power is produced. Contrary to the what some might say, ANYTHING you do to increase power on a correctly tuned engine will increase combustion heat. However, by tuning the carb rich, the engine will be cooled by the incoming fuel/air mixture, plus it'll get more oil, too.


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## gemniii (Dec 4, 2009)

JELIII said:


> I bought the whole mill set up with a double ended bar with a roller in the helper handle - I think the bar is 48", with an oiler at the other end. I am just starting to put it together. I hope this wasn't a bad choice of bars.


Now you need a dedicated helper.
That's a good setup if you've got big wood to cut.


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## JELIII (Dec 4, 2009)

I just measured the bar it is approx. 55" from the center of the roller to the saw when mounted. This gives me about 44" of cutting width. Is this too much for the 660? 



> Before you can jump to any conclusions about compression, measure the compression you have now. If it is 160 or better, then you are good. If it is below 140, then measure the squish, and depending on what you find, you might consider pulling the factory base gasket and reinstalling the cylinder to have 0.020" squish.




OK, you lost me a bit here. Why am I checking the compression? I have never done this, but I can get a gage if necessary and give it a try.

How difficult is it to remove the limit caps on the carb screws? If I can only go 3/4 of a turn on the high, I guess I will need to take it off to get to where I am a bit rich. I am starting to assume that I will need a tach to get it set with any degree of accuracy.

I have some big wood and a couple of big friends, now I just need to get them excited about milling.


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## woodsrunner (Dec 4, 2009)

JELIII said:


> I just measured the bar it is approx. 55" from the center of the roller to the saw when mounted. This gives me about 44" of cutting width. Is this too much for the 660?
> 
> OK, you lost me a bit here. Why am I checking the compression? I have never done this, but I can get a gage if necessary and give it a try.
> 
> I have some big wood and a couple of big friends, now I just need to get them excited about milling.



44inches of cut is a big bite. BUT, I would go ahead and try it. The way I see this you've already laid out the cash for the bar, chain?, the mill, the helper handle and saw. Go to it! :greenchainsaw: What will it hurt? If it is too much for the 660 you will learn that and then figure out what to do next.

If you have a pretty new saw and it runs good. I wouldn't worry about the compression unless you have some reason to think compression on the engine is low.

Big wood and big friends is the perfect combination for a chainsaw milling fiend.
Set that rig up get your guide rail system on and cut some wood. Don't overthink it too much. Remember this is fun. You will have a learning curve and rest assured you will stub your toe a time or 2, but so what? Have fun and holler at the rest of us when you run into something you can't figure out.



Scott


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## Andrew96 (Dec 5, 2009)

JELIII. The compression comment to you was because (without thinking about it), I hijacked your thread and got mixed in there. I'm sorry for that one. I'd really like to see your big long setup going in a photo. Remember your camera.


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## Andrew96 (Dec 5, 2009)

mtngun said:


> Engines produce heat, fact of life. The whole operating principle is based on heating air. The hotter the air gets, and the more air moves through the engine, the more power is produced. Contrary to the what some might say, ANYTHING you do to increase power on a correctly tuned engine will increase combustion heat. However, by tuning the carb rich, the engine will be cooled by the incoming fuel/air mixture, plus it'll get more oil, too.



MtnGun, Thanks for your comments on the loudness, and directed heat of a dual port. I had not heard about that before. I agree about the power/heat relationship. I think I might have a go at opening up my existing exhaust (I've looked at it all, and understand your comments) while retaining the spark arrestor. My milling has been done in cooler temps so that might help my saw. I won't bother playing trees until it's 10c or lower. I'll see what compression I get before I measure squish. I'll assume 160psi is about it in stock form.


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## JELIII (Dec 5, 2009)

OK so what is squish? Does it matter where I drill the extra holes in the inner cage of the muffler. I have not taken the muffler off yet, but it appears as if the inner cage can not be removed from the muffler itself. 

I bought the long bar because I have a couple of big walnut crotches to saw. I realize it would be more practical to get a shorter bar for most of my cutting. How long can I go without mounting the auxilary oiler. Any suggestions on where to get the bar and what kind? I assume this has been discussed in other threads, so I will look around.

Since it is snowing like mad here I hope to get the saw ready and the mill mounted today and give it a go tomorrow.


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## BobL (Dec 5, 2009)

JELIII said:


> OK so what is squish? Does it matter where I drill the extra holes in the inner cage of the muffler. I have not taken the muffler off yet, but it appears as if the inner cage can not be removed from the muffler itself.



Lay the saw over onto the clutch cover like you are about to mill. Stand in the milling position and look at the muffler. Avoid drilling any holes in those areas you can see on the muffler otherwise you will end up with exhaust in your face or on your arms. Ever regular mufflers are problematic on a modern saw since the exhaust bounces off the log and onto the operator. 

It's better for the operator if any exhaust mod can direct the exhaust away from the log and the operator. I describe this in this post.



> I bought the long bar because I have a couple of big walnut crotches to saw. I realize it would be more practical to get a shorter bar for most of my cutting. How long can I go without mounting the auxilary oiler.


 I run my aux oilers on all my bars (16 to 60") but these are used to cut Aussie hardwoods. Others can give you advice about your local softwoods .


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## JELIII (Dec 5, 2009)

I have read a number of other threads and posts here that recommend enlarging the existing hole, but this will be a real bi#%@ working under that small cowling on the stock muffler. Any suggestions? I am considering cutting it off and welding it back on after I enlarge the hole. There are two holes in the muffler, the round one and then a small slot in front of it. I plan to leave the slot as is and just enlarge the hole to 3/4.

I took the rubber seal away from the outside of the carb adjusters and see the limiters. How do I get them out and do they need to go back? 

I am more of a carpenter than a mechanic!


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## splitpost (Dec 5, 2009)

I run my aux oilers on all my bars (16 to 16") but these are used to cut Aussie hardwoods. Others can give you advice about your local softwoods .[/QUOTE]

:jawdrop:bobl is that a typo,hope ur not starting to slip,LOL LOL


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## danieltree (Dec 5, 2009)

Please stop and bring it to a saw shop. You said that this saw was fairly new so if i were you I would pay the guy at the saw shop to do it . It will be cheaper than burning up your saw.​


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## mtngun (Dec 5, 2009)

JELIII said:


> OK so what is squish?


How close the piston comes to touching the top of the cylinder, around the perimeter of the piston. Assuming you have a newer saw with decent compression, you don't need to worry about squish. But if you ever rebuild your saw, it is a good idea to check the squish. Hot rodders often use a thinner gasket to reduce the squish and boost compression.



> Does it matter where I drill the extra holes in the inner cage of the muffler. I have not taken the muffler off yet, but it appears as if the inner cage can not be removed from the muffler itself.


Right, the cage is spot welded to the muffler. I don't think it matters where the extra holes in the cage go, use your own judgement.



> How long can I go without mounting the auxilary oiler.


There is no right or wrong answer but I think an aux oiler is a good idea.



> Any suggestions on where to get the bar and what kind?


Baileys works for me.

Someone asked about how to enlarge the exit hole on the standard 660 muffler. I used a carbide burr in a drill, a dremel or die grinder would have been more appropriate.

Someone said you need to let the dealer tune it for you. Tuning is very important on chainsaws because they are basically cooled by the fuel mixture. If the saw is not tuned right, it overheats and you end up with a big repair bill. 

On the other hand, every saw I've ever got my hands on needed carb tuning, including a saw that had just received a dealer tune-up. If you are going to mill with a saw, you really, really need to learn to tune the carb.

Lots and lots of questions flying on this thread and I can't keep track of them all.


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## BobL (Dec 5, 2009)

splitpost said:


> > I run my aux oilers on all my bars (16 to 16") but these are used to cut Aussie hardwoods. Others can give you advice about your local softwoods .
> 
> 
> 
> :jawdrop:bobl is that a typo,hope ur not starting to slip,LOL LOL



Yep - I fixed it, 16 - 60"

Thanks


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## JELIII (Dec 5, 2009)

I will probably end up taking to a shop after I modify the muffler. I need to find a good saw shop, because the local hardware store where I bought it doesn't seem too on the ball. 

I guess it isn't necessary to remove the cowling over the exhaust hole to enlarge it?



> I have read a number of other threads and posts here that recommend enlarging the existing hole, but this will be a real bi#%@ working under that small cowling on the stock muffler. Any suggestions? I am considering cutting it off and welding it back on after I enlarge the hole. There are two holes in the muffler, the round one and then a small slot in front of it. I plan to leave the slot as is and just enlarge the hole to 3/4.



Is there a trick to removing the limiters?

Thanks again for all the help.


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## mtngun (Dec 6, 2009)

JELIII said:


> I will probably end up taking to a shop after I modify the muffler. I need to find a good saw shop, because the local hardware store where I bought it doesn't seem too on the ball.


Most of the saw shops in my area are primarily ATV dealers and saws are a small part of their business. They might have one mechanic who knows saws and the other mechanics are ATV guys. I do not assume that the dealer knows how to tune a saw correctly.



> I guess it isn't necessary to remove the cowling over the exhaust hole to enlarge it?


The cowling makes it awkward, but you can work around it with the right tools.



> Is there a trick to removing the limiters?


I think Stihl actually sells a special tool to remove limiters, dunno the part number. I screw a drywall screw into the limit cap and then yank it off, but the limit cap is usually destroyed in the process. You don't have to reinstall a limit cap, but the caps provide a better grip for your adjustment screwdriver compared to a bare screw (but trim the stops off the caps before installing them).


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## danieltree (Dec 6, 2009)

I pass 3 Stihl dealers that service saws to get to the guy i use. JELIII said his saw is fairly new so that implies warranty to me. It would almost be better to run the saw with its factory settings than to adjust the carb wrong. If you get in the phone book and find the loggers or tree services in your area and ask them who they use you might find a great saw mech.​


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## excess650 (Dec 6, 2009)

Where are you in central Pa?

As for the muffler, if you are going to modify the existing outlet, pull the front cover, pull the screen from the outlet, enlarge the outlet from the inside, clean the filings out, reinstall the screen, and then the front cover. Drilling or removing the inner cage really isn't necessary.

The DP muffler is kinda loud, but I wear muffs or plugs anyway. Letting the hot exhaust out isn't a bad idea...

As for tuning, the limiter caps will come off, and its not a bad idea to put them back on. I prefer to have my milling 066 4 stroke at 11-11.5K. If you have a tach, tune the H fully CC to the limter and check for max rpm. If its still too fast, you'll need to pull the limiter cap to make the mixture richer. The extra fuel will help to keep the saw cooler on the long cuts experienced while milling.


I've pulled the muffler and had a peek at the piston and cylinder after milling in hot weather, and the engine shows no signs of problems. I did trash a clutch spider, but something has to give.

Again, use fresh pump premium and good mix oil 40-1. I've used Echo Powerblend since it was available in gallons locally for less than $25, and it has worked well without excessive carbon, smoke, or nasty smell. The synthetic blends seem to be really good without the higher price of the full synthetics.

Let your saw idle for 30-60 seconds after a long cut so that it might dissipate some heat. Refueling, refilling the oil, and sharpening the chain are all time for the engine to further cool.


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## JELIII (Dec 6, 2009)

I am just north of Harrisburg outside of Dauphin.

I pulled the caps and removed the tabs and got them back in without a problem. I also enlarged the muffler hole to about double what it was. I am not sure how you could do it from the inside because the cage seems to be in the way. I did the best I could from the outside with a file and die grinder. I also put three new 1/4" holes in the end of the inner cage.

Any thing special I need to do to the gasket between the muffler and the head before I reinstall it?

I don't have a tach so I was going to start with the high about a 1/4 turn out past the limiter and see if I could tune it by ear. If a tach is absolutely critical I will certainly spend the $80 before I cook my saw.

Thanks for the help.


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## mtngun (Dec 6, 2009)

JELIII said:


> Any thing special I need to do to the gasket between the muffler and the head before I reinstall it?


No, nothing special, just make sure it stays in place while you get the two bolts started.

Sounds like you did everything right.


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