# MS 880 advice



## billstuewe (May 15, 2010)

For you guys that run an 880 on a mill and using a tach---what RPM do you mill at? This thing is tached at 11000rpm max no load (yes the book on this one says 11000 max no load). It seems to mill best at between 6000 and 7000 RPM. That seem too slow to me. What are you getting with yours?
This also has one of the new cast iron mufflers and it sure seem to be runnnig hot--as in the heat seems to boil off the saw. The dealer says it must be the muffler??????
Thanks for your input,


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## smokinj (May 15, 2010)

billstuewe said:


> For you guys that run an 880 on a mill and using a tach---what RPM do you mill at? This thing is tached at 11000rpm max no load (yes the book on this one says 11000 max no load). It seems to mill best at between 6000 and 7000 RPM. That seem too slow to me. What are you getting with yours?
> This also has one of the new cast iron mufflers and it sure seem to be runnnig hot--as in the heat seems to boil off the saw. The dealer says it must be the muffler??????
> Thanks for your input,



mine says 11500 just look in the manul but only had it for a couple weeks
still yet to see gas. cast muffler aswell


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## mtngun (May 15, 2010)

BobL will eventually be along to answer your question but in the meantime, here's what he said on a previous post.



> When I set up my tacho wrap handle clamp on the 880 I envisaged just using the tacho to tune the saw and then removing it but what I am finding is that I am using it a lot especially when milling big logs. With small stuff you can just sit on WOT and go for it but I don't plan to mill any more small logs with the 880 - it's just a waste of fuel when I can use 441 or 660. On bigger (40"+) harder logs *I seem to get maximum cutting speed at around 10000 - 10500 RPM* so I keep an eye on the tacho and it does seem to help, at least until I get a hang of using this saw.



Done a muffler mod yet ? I haven't seen a 880 muffler, but if it is as restrictive as the current 660 muffler, that would explain the heat and poor power.


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## BobL (May 15, 2010)

billstuewe said:


> For you guys that run an 880 on a mill and using a tach---what RPM do you mill at? This thing is tached at 11000rpm max no load (yes the book on this one says 11000 max no load). It seems to mill best at between 6000 and 7000 RPM. That seem too slow to me. What are you getting with yours?
> This also has one of the new cast iron mufflers and it sure seem to be runnnig hot--as in the heat seems to boil off the saw. The dealer says it must be the muffler??????
> Thanks for your input,



That's very interesting because 6000 rpm is where the stock 880 supposed develops is greatest torque - but as you will see below this RPM is not where you should operate the saw. As well as the performance characteristics of the engine, optimum milling speed RPM is dependent on a number of other factors including things like wood hardness, size of cut and chain settings.

Leaving cut size, engine characteristics and wood hardness aside for the moment;
If the chain has too much hook and/or the rakers are too low then the saw will have to be held back or it will bog down - this translates to fastest coolest milling being done at higher RPM.
If the chain has too little hook and/or the rakers are too high the saw will need to be pushed to cut anything which loads up the engine reducing RPM. At lower loaded RPM there is also less cooling so the saw runs hotter. I can see my saw clearly running hotter if I push it because I have a temp gauge on my saw,

I haven't milled with my 880 in completely stock form so I don't know how it compares, so my comments from here on related to my 880 which has a significant muffler mod, 19 mm versus 14 mm stock opening or an increase of 84% that exhaust can escape from. I then tune my saw slightly rich so max RPMs are 11.5k

Now that I have more experience with my 880 I realize my original comment of 10.5 - to 10k should have been "overall optimal cutting speed" rather than "fastest cutting speed"

With 6º chain cutting angles in my big hardwood, if I sit on 10k and push the saw hard it will initially cut much faster than when I'm just sitting on 10k, but then the RPMs drop and eventually at around 7 K the cutting speed slows to less than what I get at 10K. This would seem to say that I should find an even sweeter cutting speed spot somewhere in between the 7 and 10k, but it doesn't always work out like that - if I push it very hard the engine bogs down in a couple of seconds, if I push it just a little, it will still slow and usually it continues to slow and eventually bogs down. It might take 5 seconds or 10 or 20s to slow but it will slow. Now I don't want to be standing there bogging and unbogging the saw all the way through every cut. This generates an uneven finish and bluntens the chain quicker, and more significantly, heats the engine more than necessary. In practice, one does not wait until the saw has bogged and as it begins to slow of course one backs off the pressure so the RPM catch up again. Bear in mind that every time it's catching up it's not cutting as fast as it could.

If I sit the engine on a constant say 10k, the engine is getting good air flow, it's constantly cutting with a great finish and I get to the end of a slab without exerting much effort, with the chain still moderately sharp at the end. In practice if I adjust my leg pressure to push it a touch more and maybe operate in the 9.5 - 10k range it cuts a bit faster without a lot more significant effort. If I push like a demented bull and continually range the saw up and down the power range, both I and the saw end up all hot and bothered and in practice I don't end up cutting any faster overall and we just wear out for no good reason.


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## billstuewe (May 16, 2010)

I sent you a private message on this and I think we were both typing at the same time. Thanks for the input. It sounds like my 6-7000 may be about right with my stock saw. I was cutting red oak with about 16" in the cut. I will try it on the AK mill in wider pecan on Monday and let you know what happens.


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## BobL (May 16, 2010)

billstuewe said:


> I sent you a private message on this and I think we were both typing at the same time. Thanks for the input. It sounds like my 6-7000 may be about right with my stock saw. I was cutting red oak with about 16" in the cut. I will try it on the AK mill in wider pecan on Monday and let you know what happens.



In 16" cut of just about anything, a clean stock 660 running the same chain and sprocket will outcut a stock 880. This is because at 16" cutting speed is chain type and chain speed limited and the 660 will have a higher chain speed.
The 880 will do a whole lot better if you up the pin count on the sprocket (at 16" you will probably need a 9 pin) and drop the rakers to create a cutting angle of 7º.

Like I said, I would not run the 880 continually at 6-7k with that muffler as I reckon it will damage the saw in the long run.


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## mtngun (May 16, 2010)

BobL said:


> In 16" cut of just about anything, a clean stock 660 running the same chain and sprocket will outcut a stock 880. This is because at 16" cutting speed is chain type and chain speed limited and the 660 will have a higher chain speed.


I'm guilty of hijacking the thread, but my 066BB only pulls 8500 - 9000 in a small softwood log when it is setup with 3/8 chain and a 7-pin -- and only 0.023" rakers ! ! ! I find it hard to believe that a 120cc saw would not be able to better that chain speed and probably do it with more aggressive rakers, too ? 

Billstuewe, how does the new 880 compare to your old 084 ?


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## smokinj (May 16, 2010)

Ran my 880 for the first time today was running very hot as well its like the brake not disingauageing and running real hot didnt run it long will take it back to the dealer and see what they say but for sure something up my 460 would blow it away in very large wood.


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## BobL (May 16, 2010)

smokinj said:


> Ran my 880 for the first time today was running very hot as well its like the brake not disingauageing and running real hot didnt run it long will take it back to the dealer and see what they say but for sure something up my 460 would blow it away in very large wood.



Like I said to billstuewe, I presume you are running it in as per manual? I recall mine seemed a little hot too during the running in process and it was not cutting as well as I had hoped - It took about 10 tank fulls to loosen up and then about another 5 before it started to sing. Don;t forget I also have a muffler mod which helps it run cooler.

If not, it's starting to sound like the new 880s, as they say from time to time in Houston ". . have a problem".

For about $40 you can get a small battery powered temp gauge that could save a lot of heartache.


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## billstuewe (May 16, 2010)

Bobl, Where and how do you attach the temp guage probe? Can it be moved easily between saws? I put velcro on my saw handle and on the back of the tach and move it between the 880 and the 660. My tack is the same as yours.

On the heat--I think this new muffler has so much metal mass compared to the old style that it retains the heat.??????????
Here is what I amn into sawing now---


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## Deets066 (May 16, 2010)

smokinj said:


> Ran my 880 for the first time today was running very hot as well its like the brake not disingauageing and running real hot didnt run it long will take it back to the dealer and see what they say but for sure something up my 460 would blow it away in very large wood.



Wasn't happy with my 088 first tank of fuel either, even after a few tanks i wasn't impressed in 20" wood but when i put my 50" bar on and had it buried it would way out cut my 066 with 36" bar in the same log.


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## mtngun (May 16, 2010)

Anyone know if the current 880's have a limited carb ? 

Just trying to think of what else could be bogging the saw down ?


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## BobL (May 16, 2010)

mtngun said:


> Anyone know if the current 880's have a limited carb ? Just trying to think of what else could be bogging the saw down ?



They have RPM limited coils and caps on the carby screws which can easily be removed.

Re: Temp Gauge
Full thread here and yes it can be moved easily enough between saws. Ideally it should be fixed onto the jug but I haven't go round to doing that yet. 

Straight out of the box my 880 was also sluggish, hot and very tight and I was somewhat disappointed. And like I said in anything situation that is chain speed limited it seems kinda slow and dorky. If I'm cutting Less than about 18" I get the 441 with the lopro chain out - its half the effort half the fuel for not much of speed loss.

The older 880 muffler with the screw on spark arrester cover plate made it ideal for modifying the exit. How does the new one look - from memory it looks like the 660 mufler?


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## mtngun (May 16, 2010)

I'm thinking the newest 880's do have a limiter built into the carb. See this thread.

The limiter works by enrichening the fuel mix -- similar to a choke -- to prevent the saw from over revving. But even experts like JJ don't know exactly how it is controlled, or how to disable it (if you knew exactly where the circuit was, you could probably plug it with JB weld.) 

If the carb limiter is indeed the problem -- and I'm not saying it is, just kicking ideas around -- and if Billstuewe still has his grenaded 084 on hand, he might be able to do a carb swap.


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## billstuewe (May 16, 2010)

This new 880 muffler is nothing like the 660. I will take a pic tomorrow and post. 
I read the temp gauge post--Where/how did you end up mounting the sensor? Would it work to just put it on the muffler? Stick it into the exhaust port? If you stick it on the head fins, will it affect the cooling?


I just ordered my TRAXXAS gauge--$22.94 with shipping---


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## BobL (May 17, 2010)

billstuewe said:


> This new 880 muffler is nothing like the 660. I will take a pic tomorrow and post.
> I read the temp gauge post--Where/how did you end up mounting the sensor? Would it work to just put it on the muffler? Stick it into the exhaust port? If you stick it on the head fins, will it affect the cooling?
> 
> 
> I just ordered my TRAXXAS gauge--$22.94 with shipping---


Excellent.

RE: Location:
there is a gap in the fins between the cylinder and exhaust manifold shown here.




It would be better if the naked sensor was embedded in a small block of ally and then inserted/jammed into that gap but insertion will be good enough for relative work. You can stick ir anywhere as long as you compare like with like. Don't worry it won't affect the cooling.

If it can reach I would put it inside rather than on the muffler but one would need to see if it and the insulation can handle the temperature first. I have a glass fibre insulated thermocouple than can check the actual internal muffler temp but currently I am nowhere near my home. I will check it out on the weekend.


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## smokinj (May 17, 2010)

BobL said:


> Like I said to billstuewe, I presume you are running it in as per manual? I recall mine seemed a little hot too during the running in process and it was not cutting as well as I had hoped - It took about 10 tank fulls to loosen up and then about another 5 before it started to sing. Don;t forget I also have a muffler mod which helps it run cooler.
> 
> If not, it's starting to sound like the new 880s, as they say from time to time in Houston ". . have a problem".
> 
> For about $40 you can get a small battery powered temp gauge that could save a lot of heartache.



I going to take it back today I am pretty sure the brake is not fully letting off.
I cant spin the chain by hand with the brake off and boggs out on any size wood.


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## Kicker_92 (May 17, 2010)

My 880 seems to cut best when it's lightly loaded, spinning about 9,000 rpm in the cut. With the 3/8" chain and 8-pin, it's about the same chain speed at your .404 & 7-pin. 16" wide cuts though are very small for a 120cc saw.

I have not found the HT-12e to be limited. It is a semi-fixed jet carb though, and that through me for a bit. The jet has to be enlarged when I ported the saw. It is a intellicarb, so adjusts the mixture slightly as the air filter creates more resistance.

The coil limits at 11,500rpm as Bob said, which makes no differance in the cut. There are many good references here for "tuning in the cut" on here, and that seems to have worked well so far. (no more melted pistons)


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## billstuewe (May 18, 2010)

Here is a comparison of the mufflers 880 on the left/ 660 on the right






Here are two close-ups ---











I milled in a 25-30 inch cut of pecan with a 42" bar and it seemed ok, but slow. I let it run at about 7900-8350. The chain was a bit grabby and would suck the rpms down to 6000 or less if I pushed at all. I will try with a different chain tomorrow. Maybe it will get better with more tanks of gas through it as some have said.
Thanks for all the input---


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## mattfr12 (May 18, 2010)

do any you guys ever have a problem with the bolts comming off that hold the sprocket cover on while running the 880 mine seem to vibrate loose after about 30 min of running and then the sprocket cover comes off and chain comes off and i get :censored:. 

i currently am using the blue loctight to keep it from poping off called stihl and they said its just from vibration.

just wondering if any of you guys have had the same thing happen. or is something up? i know the bar isnt bent or anything because that was my first thought a slight curve causing the chain to wiggle.


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## mtngun (May 18, 2010)

How big is the exit hole ? 1/2 inch ? I'd open it up, but that's just me.








> I let it run at about 7900-8350. The chain was a bit grabby and would suck the rpms down to 6000 or less if I pushed at all.


How does that compare to your 084 ? 

You've been milling for a long time, so I presume you have proven milling chains and a good feel for how a 120cc saw should perform.

After you have used the temperature probe for a while, please let us know what you think of it, and what you have learned.


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## BobL (May 18, 2010)

mtngun said:


> How big is the exit hole ? 1/2 inch ? I'd open it up, but that's just me.
> 
> 
> 
> .



that muffler looks the same as mine. It's cast ally and the opening is 14 mm. I opened mine up to 19 mm. the saw breathes better and it seems to run better all round. 

My full muffler mod is here.
http://www.arboristsite.com/showthread.php?t=88748


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## billstuewe (May 29, 2010)

BobL said:


> Excellent.
> 
> RE: Location:
> there is a gap in the fins between the cylinder and exhaust manifold shown here.
> ...




Now that I have had time to read the directions and examine the prob/wires, it says to loop the wire all the way around the head (like a hangmans noose)and secure it around the inside of the last fin above the exhaust port where you point to on the picture. Is there enough wire to loop it around the head and still mount the sensor on the handlebar? The heat of the head won't melt the insullation on the wire?
It also says to mount it such that the sensor is located on the side of the saw, 90° to the exhaust port? And how did you mount the gauge to the saw? Velcro?
By the way, the saw IS running better and better. I emailed Stihl and got the following reply ref what RPM the saw would mill best at:

Dear Mr. Stuewe,



Thank you for contacting STIHL.



For the best performance from your STIHL MS 880, it is best to maintain the factory recommended carburetor settings for RPM. Operating this chainsaw at around the 7000 to 8000 RPM range under load should produce the best power, torque and provide adequate cooling. As your chainsaw gets more time on it, the engine will continue to break in and have even better power.



Thank you for using STIHL Products.



Regards,



Stuart Lumpkin

Technical Manager

Blue Mountain Equipment – STIHL

972-548-9045 Ext 104



Thanks,


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## BobL (May 29, 2010)

billstuewe said:


> Now that I have had time to read the directions and examine the prob/wires, it says to loop the wire all the way around the head (like a hangmans noose)and secure it around the inside of the last fin above the exhaust port where you point to on the picture. Is there enough wire to loop it around the head and still mount the sensor on the handlebar?


Unfortunately the wire loop is not long enough to do this.



> The heat of the head won't melt the insullation on the wire?


The insulation appears to be some form of telfon which will remain solid up to a temperature of about 450F. If the outside of your head reaches this temp then the saw will be toast. 



> It also says to mount it such that the sensor is located on the side of the saw, 90° to the exhaust port?


This is suggested to give some average reading, but for chain saws we are more interested in the highest reading since it is the highest temps that cause problems. There are some temperature sensors that attach to the spark plug or replace the spark plug ring, but this is not the hottest part of the the engine which is somewhere in the the exhaust manifold or even into the exhaust where the combustion front reaches its max burn rate. This is why I decided to tuck the sensor inside the gap between the top of the exhaust manifold and the nearest fin. This is as close as I could get to the most temp sensitive part of engine, ie the top edge of the piston at the point where the exhaust gasses escape. 

Ideally the sensor should be mounted inside the exhaust itself which would measure the temperature of the exhaust gasses and also make it suitable for tuning. There are exhaust gas temperature (EGT) sensors specifically designed to do this but they have fibreglass insulation because EGTs can reach over 1000F and this will definitely melt any teflon insulation. 

To locate the Traax sensor outside the engine, one possibility is to drill a small hole in the exhaust manifold itself but I am still thinking about that. The other possibility is to embed it in a small ally block to jam in between two of the fins or between the the top of the exhaust manifold and the nearest fin. This would give a truer reading than doing what I have done because my sensor reading is affected by the cooling air generated by the fan. I don't think this really matters much since any external temperature sensor placement is a relative exercise anyway, so unless an EGT is used, the absolute temperatures don't mean much, it's the differences and changes that are important.

Here's how I cabled the sensor to the saw. I used a round file and made a 3/4 round notch in the base of the top plastic cover and then used one of the supplied pieces of silicone tubing to protect the wires at that crimping point. See arrow on LHS. 







> And how did you mount the gauge to the saw? Velcro?
> The gauge is mounted to the same stand as my tacho stand described here.
> I attached a piece of 1/16" ally plate to the stand underneath the tacho. The plate has a small offset to allow for the temp gauge to sit alongside the tacho. I just used a thick double sided tape but velcro would be better because if you leave the gauge on it will flatten the battery and then being able to take it off and remove the back of the gauge to replace the battery will be easier
> 
> By the way, the saw IS running better and better.



That's great.


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