Stihl MS 661C

[charles.mann]

I did try the search function before asking this question. Only similar reference i found was for 461.

I have a 2016 661C that i truly thought was a manual carb. After installing a maxflow filter, i opened the side up to adjust the carb and found a damn elec connector, then saw some extra wiring and another connector on the coil. I took the carb shroud off and found a bunch of wiring attached to the carb, telling me its an m-tronic carb, even though i requested a manual carb when ordering.

Even though it an m-tronic, and following the operator manual and the instruction on the maxflow website, the saw did not act as if its an m-tronic, as per what the manual said the saw would do when calibrating.


Two questions
1. Are all C series 661s m-tronic? I was under the impression a CM was m-tronic, not a regular C.
2. What are the difficulties swapping an m-tronic over to a manual carb and coil and which carb and coil do i need? The stihl ipc shows 3 different carbs (WJ-140 p/n 1144 120 0612, above s/n 1843****, my saw s/n is a 181852351) and what looks to be 2 different m-tronic carbs since they both say p/n 1144 007 1801, item #30 svc kit, m-tronic (showing a coil pack, what looks to be fuel filter pickup body, and some kind of solenoid valve, that looks like a 2 prong fm elec connector and 3 different coils item numbers 7, 8 and 9 with only 8 p/n 114 400 4704, control unit (above 187780674) and 9 p/n last 4, 4704, control unit (up to s/n 187780673).


I am wanting to port the cyl head and add a better breathing muffler. Just wanting to get all my ducks in a row and check for parts availability and get ordered what i need to order.

 

[ElevatorGuy]

The c is mtronic, they don’t put the m on the saw.

 

[charles.mann]

The c is mtronic, they don’t put the m on the saw.

According to my operator/instructional manual downloaded by the stihl deal, according to my s/n, there is an M.


Either way though, it is not what i asked for, but 6 yrs to late. Now its time to dump the electronics and go manual.

 

[maulhead]

According to my operator/instructional manual downloaded by the stihl deal, according to my s/n, there is an M.
View attachment 348229

Either way though, it is not what i asked for, but 6 yrs to late. Now its time to dump the electronics and go manual.

They refer to them as C-M in literature, and on their website.

But they don't put the M on the recoil badge on the saw, only the C, as the other poster said.

Any time you see C on the recoil after the numbers that means it's mtronic, 201tC, 241C, 261C, 362C, 400C, 441C, 462C, 661C, are all mtronic.

They do make a non mtronic adjustable carb 661, and it just says 661 on the recoil badge.

 

[charles.mann]

Well now that i know the C denotes electronic crap, even though opening it up i figured out myself it was electronic, i now need to know which carb and coil i need to order. If no one on here responds by tomorrow, i’ll go to one of the stihl dealers and ask them.

The past 2 days, I’ve tried getting ahold of the guy that I planned on doing the port work but no answer. I was hoping he could answer the carb and coil question, and maybe he can, but if i can't get ahold of him to confirm, i’ll go the route of the dealer, order it, install it and go from there.


Can a 661 electronic saw be ported and the electronic crap still be able to do its thing?
The guy for the porting said he could build it for felling, milling or a half and half, but wont be good/better at either if built to a blended role. IDK enough to say for certain either way, which route would be the best option. I do plan on getting a knock off china made 880 clone for milling till/if i burn it up. Till then, the 661 is just gonna have to do the job.

 

[Blackgreyhounds]

Yes, electronic carb control saws (Stihl M-tronic, Husq Auto-tune) do just fine after porting.

 

[ElevatorGuy]

I’d port your m saw and be done with it. It will probably run better than the adjustable carb you seem to want.

You said 6 years too late, how do you own a saw for 6 years and not know it’s mtronic?

 

[Hinerman]

I’d port your m saw and be done with it. It will probably run better than the adjustable carb you seem to want.

You said 6 years too late, how do you own a saw for 6 years and not know it’s mtronic?

Took the words right out of my mouth...

 

[charles.mann]

You said 6 years too late, how do you own a saw for 6 years and not know it’s mtronic?

I dont see the reference as to my inquiry for a crab and coil. But if you absolutely must know.

I use 1-2x a yr when i have trees greater than 30” to fell and buck. I clean the filter and replace the plug, fuel/oil it and go cut.
Iv nvr had a problem out of it that would require opening more than the air filter cover and clutch cover.

Does that suit your question as to why i havent opened it any further and didnt know it was electronic?

 

[ElevatorGuy]

Two questions
1. Are all C series 661s m-tronic? I was under the impression a CM was m-tronic, not a regular C.


I answered your first question…

 

[charles.mann]

Yes, you did. I answered your question too, as to owning something for and not knowing what it was. I thought that was pretty clear by quoting your question. I still do not see what owning my saw and not knowing it was elec has to do with the p/n for a manual carb and coil.
If you dont know, cool beans, no worries, I went to the stihl dealership and got them.

 

[Loony661]

I don’t mean to step on your toes here, but in my opinion, if you truly wanted an adjustable carb model, wouldn’t it just be easier to sell your 661C for $1000 and order/buy the Std 661 from a dealer for a couple hundred bucks more? Then you would be started with a brand new saw again. And if you truly only use your current saw 1-2 times a year, it should be in great shape to bring top dollar as a used saw.. Just my 2 cents..

I have a 2015 661C myself and it has also been flawless. Super reliable, powerful, never lets me down. I have a muffler mod and a MaxFlow on mine as well. So maybe if yours has also been a great saw, just have this one ported as-is and run it.

 

[charles.mann]

@Loony661
You arent stepping on toes. As you said with your saw, mine too has been a very good saw for what i ask of it. Since it is a good saw, im not for selling it. I more than likely will have it ported as is, but i also want to have a manual set up on hand as a back up.


According to the guy that is to do the porting, if he built it as a felling saw, if i were to use as a milling saw, it would get hot and possible damage it. He said id have to richen the fuel to help keep it cooler. With the m-tronic, i dont think it would be possible to manually adjust the mixture.


It seems the two guys iv spoken with on porting, wont mod those clone saws without putting oem parts and with the pricing of oem parts, id be into a clone saw 3/4 the cost of a new oem saw. With that much into a clone, i might as well just buy an oem saw.

 

[Int1968]

Idk an mtronic or auto tune will keep the saw run with pretty substantial air leaks. Mike CFB did a 261arctic for me that’s mtronic and it’s a ripper( it gets used for climbing and firewood (jackpine, tamarack, birch)).

Building a ported work saw is different from a cookie cutter which is different from a milling saw.

Talk to your builder and tell him want your gonna do with it, and what type of wood you’ll be cutting. You’ll be happy and they’ll have a clear direction of your expectations and needs.

 

[Loony661]

@Loony661
You arent stepping on toes. As you said with your saw, mine too has been a very good saw for what i ask of it. Since it is a good saw, im not for selling it. I more than likely will have it ported as is, but i also want to have a manual set up on hand as a back up.


According to the guy that is to do the porting, if he built it as a felling saw, if i were to use as a milling saw, it would get hot and possible damage it. He said id have to richen the fuel to help keep it cooler. With the m-tronic, i dont think it would be possible to manually adjust the mixture.


It seems the two guys iv spoken with on porting, wont mod those clone saws without putting oem parts and with the pricing of oem parts, id be into a clone saw 3/4 the cost of a new oem saw. With that much into a clone, i might as well just buy an oem saw.

The MTronic saws adjust the mixture 7 times per second (as claimed by STIHL) and I know that the main measure for mixture adjustment is the RPM based on the flywheel, and the throttle position. It’s a very simple, and yet effective way to keep the saw in-tune all the time. I don’t personally mill with mine, but I don’t see how it would run too lean, even under long, high load operation.

 

[charles.mann]

Idk an mtronic or auto tune will keep the saw run with pretty substantial air leaks. Mike CFB did a 261arctic for me that’s mtronic and it’s a ripper( it gets used for climbing and firewood (jackpine, tamarack, birch)).

Building a ported work saw is different from a cookie cutter which is different from a milling saw.

Talk to your builder and tell him want your gonna do with it, and what type of wood you’ll be cutting. You’ll be happy and they’ll have a clear direction of your expectations and needs.

Already talked with him as stated in a couple of my previous post.

 

[charles.mann]

The MTronic saws adjust the mixture 7 times per second (as claimed by STIHL) and I know that the main measure for mixture adjustment is the RPM based on the flywheel, and the throttle position. It’s a very simple, and yet effective way to keep the saw in-tune all the time. I don’t personally mill with mine, but I don’t see how it would run too lean, even under long, high load operation.

I kinda understand, from the flying side on extremely hot days, which was most of my fixed wing flt training. During cruise, we’d lean our mixture to achieve better fuel burn. But on the hotter days, other than in cruise, we’d have to richen the mixture to bring the cht down. For helicopters, we run the mixture full rich which helps keep the cht down. i can see how during milling, under high power slow speeds with a lean mix, the cht would be higher, with limited airflow coming across the ch fins.

With running 100LL, i try to mill or fell with the wind to my back, to help blow the exhaust away from me. But i cant count on wind with enough spd to help keep the cht temps down. I cant remember if it was here or on a sawmill forum, where recommendations of using a fan to blow exhaust fumes away, and help with airflow over the saw.


I can only go off of what the builder tells me, a d with no exp on modding saw, id take the info a builder says over second guessing them.
Things may change once i inform him it is an m-tronic, not a man carb, if i can ever get ahold of him. I was gonna fly to work with the saw, but the airlines, according to their website, require the saw be in its original packaging. If i could get ahold of him, i was going to let him know i wouldnt be dropping it off when he and i made arrangements. I dont like being a no show but if iv made numerous efforts in making contact well prior to the show time, i see it as not my problem and try later or find someone else.

 

[Int1968]

Same with camping stoves when flying, it’s a no go unless it new/never used

 

[charles.mann]

Same with camping stoves when flying, it’s a no go unless it new/never used

Which is what i wanted to discuss with the guy. Plan was to fly up, drop it off to on the way to work and pick it up once he is done.
Id like to discuss with him a change in plan, which is to drive to idaho, drop it off to him and use my last few days of off time to do some scouting for next yrs elk and deer season, then pick it up when he is done and drive back to tx after my work shift is over, just in time for back surgery.

 

[Yukon Stihl]

Same with camping stoves when flying, it’s a no go unless it new/never used

Take it apart,then it's a box of parts.