MS661 coil/module update required for 4700C?

[BradSt]

I have an MS661 that I bought new in 2015. I primarily use it for milling 16-20" hardwood logs. It is completely stock, and has been trouble free. I read the threads about the new coils/modules and solenoids. Mine has the original 4700C coil, that has been known to lean seize some saws. The piston wash looks plenty safe, and there is no visible scoring in the cylinder. I actually think there are times where the saw is a little fat, especially at part throttle. It runs WOT for 5+ minutes at a time. You'd think if it were a problem, I'd have seen it by now. FWIW, the saw is only run on fresh 89+ pump fuel.

With that said, is it worth updating mine to the latest "kit" with the new coil, solenoid, and fuel filter? At a bare minimum, I suppose I should install the new filter, with a finer micron rating. I'd hate to install the new module, and have it fatten the saw up, when it isn't necessary, but I'd also hate to lean seize the saw, down the road, when the 4700C's have been known to be a problem.

Any input from those who have upgraded from a 4700C, on a properly running saw, to the latest V3 module?

Thanks

 

[gary courtney]

I have an MS661 that I bought new in 2015. I primarily use it for milling 16-20" hardwood logs. It is completely stock, and has been trouble free. I read the threads about the new coils/modules and solenoids. Mine has the original 4700C coil, that has been known to lean seize some saws. The piston wash looks plenty safe, and there is no visible scoring in the cylinder. I actually think there are times where the saw is a little fat, especially at part throttle. It runs WOT for 5+ minutes at a time. You'd think if it were a problem, I'd have seen it by now. FWIW, the saw is only run on fresh 89+ pump fuel.

With that said, is it worth updating mine to the latest "kit" with the new coil, solenoid, and fuel filter? At a bare minimum, I suppose I should install the new filter, with a finer micron rating. I'd hate to install the new module, and have it fatten the saw up, when it isn't necessary, but I'd also hate to lean seize the saw, down the road, when the 4700C's have been known to be a problem.

Any input from those who have upgraded from a 4700C, on a properly running saw, to the latest V3 module?

Thanks

updated mine and could not be happier. i run 32:1 schaeffers 9000

 

[Iceboy]

I updated mine to V3. That means that got the coil-solenoid-filter changed. I did it in two stages. First I upgraded the pick up body and the solenoid valve due to having hot start issues. Later on the coil went dead. So now I have the new M-Tron version. I am happy the way she runs.

 

[huskihl]

4700C was one of the bad ones I believe. @redbull660 will know

 

[BradSt]

Looks like my local dealer wants $110 for the kit, so I just want to make sure it's worth it, and really needed. Was hoping to get a deal on it, but it doesn't sound like they'll bite. I have purchased quite a few pieces of Stihl equipment from various dealers, and rarely get anything for less than MSRP, unless it's an official Stihl promotion.

 

[BradSt]

I ordered the update kit, and will report back, once I have some time to install it and run the saw.

On a side note, I was browsing the new saws while waiting for the parts department, and low and behold, there was an MS241 on the shelf...I've wanted one of these saws for a while, but just couldn't justify it, when I already have an OE 261. Since it is discontinued and it was their last one, I figured that I had better grab it. It is a 2016 model and had been on the shelf for a while, so I was able to get a few bucks off of it, along with a doubled warranty. Feels significantly lighter than my OE 261, and should make a nice limbing saw for a bunch of evergreens that I have to take down. Came with a 16" bar and 63PS3 chain.

With all of that said, is it advisable to install the new "orange" fuel filter on this 241? It looks like the 241 doesn't have the same Mtronic issues that the 362 and 661s have had.

 

[DND 9000]

Yes that would be a good idea to protect the valve from tiny dirt particels. If you buy replacement pickup bodys now (the big one), you only get the newer orange ones. The white pickup bodys are NLA.

 

[BradSt]

So I was cleaning up the 661, and decided to inspect the piston wash again, as I had done some milling recently. The wash is definitely much smaller than I had remembered, indicating that it is running leaner than I thought. Glad I got a pic of it, so i can compare it when I change the coil. Not what I'd call dangerously lean, but not a whole lot of safety margin either. I don't run my traditional carb saws quite this lean.

 

[BradSt]

Just wanted to update this post, so it is complete...I installed the update kit, and decided to do a muffler mod as well. Drilled the spot welds on the baffle, and got that out of there. That wasn't a fun process, that's for sure. Used a sharp drill bit on most of them, and a carbide burr on a few at the top. Also used the burr to open the stock outlet to about double the area of the original. I can still use a screen if need be, in the original location.

The coil/module has 4702A on it. I warmed up the saw, then calibrated it. Proceeded to buck up a 30" oak log. Can't say I noticed any difference in how the saw ran. I did notice that it still has the little surge when coming out of a long cut. I'm guessing that is due to the Mtronic transitioning the fuel control solenoid from WOT fueling to idle fueling. It isn't an issue, just something I noticed. Also surprised how much louder it is than stock, with the muffler mod. Not sure if it was the baffle removal, the enlarged opening, or both that was responsible for this. I only use it in the woods with hearing protection, so it's not objectionable, but my smaller saws that get used in residential areas will keep their stock setups.

When i get a chance, I will check piston wash again, just to see if it has changed. I put a tank through the saw over the weekend, so it should be noticeable if WOT fueling is different. Overall the saw still runs well, and I look forward to many more years of troublefree use.

 

[BradSt]

It's been 3 years on the new module now, and I just finished milling some logs, and wanted to take a look at the piston and cylinder after a few hours of straight WOT use. Doesn't look like it has really changed, so that makes me question if the new module really does add more WOT fuel. If this were a manual carb, I'd turn the H speed screw out a tad, but it clearly lives fine like this. Bottom side of the piston is clean too. Fuel is always 89 ethanol free and oil is 40:1 Citgo Sea and Snow. I usually pay about $15/gallon for it. I gave up running boutique 2 stroke oils about 15 years ago, and have used this exclusively in all of my 2 stroke and 4 mix engines. Can't see in the pics, but all internal parts had a thick film of oil on them. Exhaust port is also very clean.

There are those that say you shouldn't mill with an Mtronic. This saw has spent about 95% of its life that way. Only mod is a muff mod.

Haven't recalibrated the saw since the first time, and I haven't had any issues with it. Still have the old style carb boot as well. Still looks ok in there.