“New” MS661 non-Mtronic vs MS661C

[bigjohnintexas]

I purchased a brand new, from the dealer, MS661 on Monday. Been kinda hard to find so I pulled the trigger. Thought it was a 661C when I purchased it, tag on shelf said 661C, receipt says 661C-M. I noticed today when looking it over that it has jet screw holes in the side cover which my 261C does not. So, after a little research tonight, it appears that they are now selling a 661 non-mtronic. I didn’t even realize this was an option.

Here’s the thing….. I really like my 261C. I have zero complaints about the Mtronic. I thought this was the CM version and that’s what I wanted. I’m sure the shop will work with me as I haven’t even sunk it into the first piece of wood yet. I’ve done 3 heat cycles at 3/4 throttle to break it in, and that’s it. But, should I keep this or ask for a swap/refund? He had one other 661 there that was a wrap handle and I’m not sure if it is mtronic or not.

I don’t necessarily mind tuning my saws. One of my 460’s I split the cases on and completely rebuilt and ported it myself. Ive rebuilt quite a few top ends, etc and have a tach to tune my saws. That being said, I’m going to mainly use the 661 for milling so it’s not going to be a play saw, and for that a mtronic sounds perfect. Are there any other differences of the 661C over this saw other than the auto carb? I’m guessing mine has the updated oiler because it throws oil on the bar like I’ve never seen before. How much better on fuel would the 661C be for milling which is primarily wide open anyway?

WWYD? Opinions and advice appreciated.

 

[link]

Milling you want to keep it, that said I love my 241cm.
The cm is probably better anyway, but there is a comfort in being able to rich it slightly if you want to.
I would be happy either way, not sure the theory of running the saw rich versus continually optimally adjusted is a good thing or not though.
I like to have control, but wow that 241cm really works in all situations.

 

[bigjohnintexas]

I spoke with the dealer today. He said the other 661 he has with the wrap handle is a 661CM and that he'd be glad to swap me because he'd rather have the one I purchased to sell. According to him, most people prefer the non-mtronic in the big saws. For the reason T.K. stated, he also said for milling I want this saw so I can fatten the top end. He also said that parts are a lot cheaper in the long run which he is probably right. So, I think I'll keep it for now.

 

[sbhooper]

Probably not a bad idea to keep it for the milling. That is hard on saws and a bit richer would not be bad. The parts thing does not sound right to me. Except for the electronic carb, the parts should all be the same. That was crap, that it had a cm tag on it, though.

 

[stihlaficionado]

I purchased a brand new, from the dealer, MS661 on Monday. Been kinda hard to find so I pulled the trigger. Thought it was a 661C when I purchased it, tag on shelf said 661C, receipt says 661C-M. I noticed today when looking it over that it has jet screw holes in the side cover which my 261C does not. So, after a little research tonight, it appears that they are now selling a 661 non-mtronic. I didn’t even realize this was an option.

Here’s the thing….. I really like my 261C. I have zero complaints about the Mtronic. I thought this was the CM version and that’s what I wanted. I’m sure the shop will work with me as I haven’t even sunk it into the first piece of wood yet. I’ve done 3 heat cycles at 3/4 throttle to break it in, and that’s it. But, should I keep this or ask for a swap/refund? He had one other 661 there that was a wrap handle and I’m not sure if it is mtronic or not.

I don’t necessarily mind tuning my saws. One of my 460’s I split the cases on and completely rebuilt and ported it myself. Ive rebuilt quite a few top ends, etc and have a tach to tune my saws. That being said, I’m going to mainly use the 661 for milling so it’s not going to be a play saw, and for that a mtronic sounds perfect. Are there any other differences of the 661C over this saw other than the auto carb? I’m guessing mine has the updated oiler because it throws oil on the bar like I’ve never seen before. How much better on fuel would the 661C be for milling which is primarily wide open anyway?

WWYD? Opinions and advice appreciated.

I have both. I'd say the M Tronic has a bit faster throttle response, but that's it
The standard carb 661 was $16 more, both R models

 

[Woodslasher]

Probably not a bad idea to keep it for the milling. That is hard on saws and a bit richer would not be bad. The parts thing does not sound right to me. Except for the electronic carb, the parts should all be the same. That was crap, that it had a cm tag on it, though.

Have you ever bought the electronic parts? I’ve heard they are very, very $$$$!

 

[SAWMIKAZE]

I don't think the 3/4 throttle thing is a very good idea...

 

[Cody]

I don't think the 3/4 throttle thing is a very good idea...

It's not.

 

[Captain Bruce]

I spoke with the dealer today. He said the other 661 he has with the wrap handle is a 661CM and that he'd be glad to swap me because he'd rather have the one I purchased to sell. According to him, most people prefer the non-mtronic in the big saws. For the reason T.K. stated, he also said for milling I want this saw so I can fatten the top end. He also said that parts are a lot cheaper in the long run which he is probably right. So, I think I'll keep it for now.

Wise choice grasshopper. As has been pointed out, adjustable carburetors on powerful engines are all around us. Drag racing especially. You will definitely tweak that fuel at some point, for more of the already available power that engine is offering.
The M-tronic and Autotune systems are solely meant to meet fed. req'mts. Anything to reduce the pleasant smoke we so enjoy while sawing. The premise has merit and rightly so. Its great tech for the saws that don't get used much to begin with. Big Box home-owner-grade machines, etc. I will go check into that 241C-M......

Anyway, I had a customers 661CM on the bench 2 yrs. ago, and was guided by fellow forum members to repair it. The M-tronic system single issue is its components. The wiring is tiny, the sensors costly, the fuel filter different, etc. Once I finished the re-cond, and followed the scary instructions for starting it was/is truly a wood warrior.

 

[bigjohnintexas]

I don't think the 3/4 throttle thing is a very good idea...

Please explain.

Since I didn't go into any detail, I'll clarify my break in procedure for every saw, motorcycle, trimmer, nitro-RC, and pretty much anything else with a small motor that I buy new.
1. I like at least 3 heat cycles before WOT to "set" the parts and let all the parts synchronize. I get it, in a perfect world all parts hold .0001 tolerances and there is nothing in a bind, but in our world...
2. I typically run 2-strokes at 1/4-1/2 throttle for the first couple of heat cycles (<5 min), never letting my throttle duration last longer then 2-3 sec so I'm always getting a fresh charge in the bottom end and never letting it idle. Small blips.
3. After 3ish heat cycles (typically 2 days), I increase those heat cycles in length while working my way toward WOT, and by my 4-5th heat cycle I'm at WOT, then I like to let the motor cool completely.
4. Let'er rip.

When I posted the original post, I had about 3 heat cycles and was at 3/4 throttle. Next cycle or two I'll go to WOT.

I don't always get that many heat cycles, but I try to. The thing I think I hate the most is hearing someone start a motor, any motor, and instantly go to WOT. And yet, I have a friend in his 70's who raced dirt bikes way back with John Penton and still rides regularly, and he does exactly that with his 2-strokes. His knowledge of motors far exceeds mine and he has a KTM200 with over 200hrs on the factory piston.

So, I'm Interested to hear other's opinions.

 

[bigjohnintexas]

Wise choice grasshopper. As has been pointed out, adjustable carburetors on powerful engines are all around us. Drag racing especially. You will definitely tweak that fuel at some point, for more of the already available power that engine is offering.
The M-tronic and Autotune systems are solely meant to meet fed. req'mts. Anything to reduce the pleasant smoke we so enjoy while sawing. The premise has merit and rightly so. Its great tech for the saws that don't get used much to begin with. Big Box home-owner-grade machines, etc. I will go check into that 241C-M......

Anyway, I had a customers 661CM on the bench 2 yrs. ago, and was guided by fellow forum members to repair it. The M-tronic system single issue is its components. The wiring is tiny, the sensors costly, the fuel filter different, etc. Once I finished the re-cond, and followed the scary instructions for starting it was/is truly a wood warrior.

Thanks for the reply. I'm definitely not scared of a carburetor. Was more concerned that the non-mtronic was either detuned, had a thicker head gasket, older style head, etc. It seems like I get the best of both worlds....newest technology head design and saw with a simple carb. Also, had not considered that it might be better to run a little fatter on the top for those long pulls while ripping boards which I could not adjust on the CM. That's the exact type of information I was looking for that I got from this forum.

And btw- I've never heard of the 241C-M that T.K. mentioned. I was referring to my 261C-M that I love. That little saw just rips.

 

[Dennisthemenace]

C =comfort ie, in this case, elasto start.
M =m-tronic
Therefore no M on the compliance plate or advertising = non m-tronic

 

[sbhooper]

Have you ever bought the electronic parts? I’ve heard they are very, very $$$$!

Nope. Hopefully, I won't have to.

 

[Gord404]

Nice to have a choice, imo , I would like to be in control of my own carb adjustments.

 

[cscltd]

Reason for not recommending part throttle for break-in or long periods of use on a saw is no part throttle jets on most saws. So at part throttle saw is receiving very little fuel from main high speed nozzle compared to air ratio at said throttle as compared to idle or full throttle (which have there own circuits)
And since lubrication and cooling is dependent on amount of fuel reaching the internals, hence the potential problem.
Burping the throttle helps but I would just let it idle for a few tanks and avoid no load full throttle.
Does mtronic fuel control help remedy this issue, I’m not sure- but don’t think it does? It may not apply to ms500i being fuel injection.

 

[Parkerpusher]

I like Autotune and mtronic saws, but I think you made a good choice keeping it. I definitely prefer a carb for milling.

 

[arborist]

Please explain.

Since I didn't go into any detail, I'll clarify my break in procedure for every saw, motorcycle, trimmer, nitro-RC, and pretty much anything else with a small motor that I buy new.
1. I like at least 3 heat cycles before WOT to "set" the parts and let all the parts synchronize. I get it, in a perfect world all parts hold .0001 tolerances and there is nothing in a bind, but in our world...
2. I typically run 2-strokes at 1/4-1/2 throttle for the first couple of heat cycles (<5 min), never letting my throttle duration last longer then 2-3 sec so I'm always getting a fresh charge in the bottom end and never letting it idle. Small blips.
3. After 3ish heat cycles (typically 2 days), I increase those heat cycles in length while working my way toward WOT, and by my 4-5th heat cycle I'm at WOT, then I like to let the motor cool completely.
4. Let'er rip.

When I posted the original post, I had about 3 heat cycles and was at 3/4 throttle. Next cycle or two I'll go to WOT.

I don't always get that many heat cycles, but I try to. The thing I think I hate the most is hearing someone start a motor, any motor, and instantly go to WOT. And yet, I have a friend in his 70's who raced dirt bikes way back with John Penton and still rides regularly, and he does exactly that with his 2-strokes. His knowledge of motors far exceeds mine and he has a KTM200 with over 200hrs on the factory piston.

So, I'm Interested to hear other's opinions.

Every saw I've bought, I started right in using it, ripping and tearing and making me money. No babying anything. Generally I'll let them run for a bit when first cold started, but often not even a full minute until I full force. I figure a top end is cheap and a shop can put a jug and piston in for just a few bucks for me. When time is money, a few bucks a year in parts is nothing.
That said, I've only had a top end of a saw replaced once and it wasn't because it was worn out, it was to turn a 334T aborist saw into a 338xpt and after I did that, the then older saw still went for many more years, until they told me the bottom end wasn't worth or couldn't be repaired. I just ran that one right out of the gate hard too. I don't even think I got a good quality top end either. Just a cheap one cus the saw was old and it still went years before the bottom end went out!
Maybe I seem to have had to replace the top end of my 346xp after several years of hard daily use. I loved the saw and wanted to keep it going and to have it repaired was less than half a new saw, so I did that but who knows how many hours I had on that thing before than happened. Years and years of daily use. Then her bottom end went and they told me that one couldn't be repaired either.

But as for just buying an running a saw, that's all I do. My saw lasts for years and years, running commercially. I always use stihl HP ultra mixed 50:1 with no exceptions. I think about the only saws of mine that get a couple min warm up are my aborist saws, cus I do start them and let them idle while setting up to climb. Saws down on the ground, start pull, wait at least a few seconds, but time is money and top ends are cheap I figure and since I'm not going through top ends, I ain't changing nothing until I do lol

I have a 395xp on the way though, and I'll confess, this one will be papered cus I know I'll probably have it for 20 years since it's only coming out for the monster trees and stumps, then put back way. I'll let her idle and warm up a couple mins first but I've no plans for a baby and concerned brake in like you either. Her top end can be replaced without me crying in 5 to 10 years. She'll have made me far more that crying over a new jug and piston will be like crying over spilled milk.
But point being; I don't baby nor outright abuse my saws but they hardly require any "real" work until they're done for. (Catastrophic failure of the bottom ends, broken, irreparable cases, after many, many years of commercial use, and bought and payed for thousands and thousands of times over.)

 

[cookies]

I like running them a few times until warm after a rebuild to heat cycle it to make sure everything is 100% and restarts easily then I warm it up and set the wide open throttle max rpm on the H needle. After that I go cut wood and work the saw hard to fine tune it after its fully heat soaked. A cold saw needs less fuel than a heat soaked saw to make it 4 stroke at the max rpm, approx 1/16 of a turn more on the h needle. As the saw fully breaks in over the next 10 tanks it will need more fuel on the h needle because compression increases. Every 35-40 degree temp change the saw will need a retune, elevation changes require a retune as well.

 

[MOOSETRAX]

Please explain.

Since I didn't go into any detail, I'll clarify my break in procedure for every saw, motorcycle, trimmer, nitro-RC, and pretty much anything else with a small motor that I buy new.
1. I like at least 3 heat cycles before WOT to "set" the parts and let all the parts synchronize. I get it, in a perfect world all parts hold .0001 tolerances and there is nothing in a bind, but in our world...
2. I typically run 2-strokes at 1/4-1/2 throttle for the first couple of heat cycles (<5 min), never letting my throttle duration last longer then 2-3 sec so I'm always getting a fresh charge in the bottom end and never letting it idle. Small blips.
3. After 3ish heat cycles (typically 2 days), I increase those heat cycles in length while working my way toward WOT, and by my 4-5th heat cycle I'm at WOT, then I like to let the motor cool completely.
4. Let'er rip.

When I posted the original post, I had about 3 heat cycles and was at 3/4 throttle. Next cycle or two I'll go to WOT.

I don't always get that many heat cycles, but I try to. The thing I think I hate the most is hearing someone start a motor, any motor, and instantly go to WOT. And yet, I have a friend in his 70's who raced dirt bikes way back with John Penton and still rides regularly, and he does exactly that with his 2-strokes. His knowledge of motors far exceeds mine and he has a KTM200 with over 200hrs on the factory piston.

So, I'm Interested to hear other's opinions.

I did read in some forum(may be hre) in the past that saws should not to be run WOT for 1st 3 tanks, as it takes 3 tanks to settle in/break in.

 

[trains]

when breaking in a new saw, warm it up, then cut at wide open throttle, just let it eat wood at its 9000rpm ish cutting speed.
let cool off for 20 or so seconds before shutting down.

dont wide open throttle no load a new saw, just let it eat wood.

you need to seat the rings, only wide open throttle and load does that effectively.
the bearings are hardened roller, not soft shell like in other motors ie 4 stroke, which require a different type of break in proceedure.

running at idle for prolonged periods of time do nothing to help the new motor seat rings at all, just waste fuel and time.

warm it up, let it cut, let it cool and enjoy it.