Unlimited 661

[fordf150]

I'm currently chasing both paths of making the MTronic work like it should and making a standard adjustable carb version. I believe there are a lot of "old school" guys out there that would really appreciate the opportunity to have a standard carb on their new 661. Time will tell how this will work out. I have a friend in Germany that is installing the non-MTronic carb an coil on his ported 661C. He's been experiencing the same symptoms. There are others as well on both ported and stock saws. Is MTronic at fault? I don't know that yet, but I sure aim to find out. It's the least I can do for my customers.

Lots of time spent working on the old lean burn chryslers and such says that there are going to be lots of instances that a mtronic/autotune isnt going to run perfect. those old electronic controlled carbs ran great 95% of the time but there is a limit as to what they were able to tune out. chainsaws are in some ways much more finicky than a 4 stroke engine. mtronic is a much simpler design with less inputs and outputs. my money says a standard carb and coil would solve every running issue these saws have and at the same time sacrifice very little if any performance.

 

[blsnelling]

I have a well broken in and good running stock 661 coming my way, graciously offered by a very generous customer of mine, with instructions to do whatever I needed. One way or another, I will narrow this down. It's going to require a ton of work and time, but it's got to be done. You know, for the good of the community and all

 

[Mtthwvn]

I hope either the thread opens back up or this one takes off and a decent conversion comes out of it...I'm really interested in seeing this puzzle solved!

So brad are you going to try to adapt the unlimited coil to the mtronic system? I think I asked in the previous thread but it was locked before it had a chance to be answered.

 

[blsnelling]

I do plan to install an unlimited coil, but that will definitely only work with the standard carb.

 

[big t double]

Did you disconnect the carb controller completely from the module or just let it dangle in the carb box?

 

[blsnelling]

Did you disconnect the carb controller completely from the module or just let it dangle in the carb box?

The solenoid must stay attached, other wise the coil will kill spark.

 

[Mtthwvn]

I do plan to install an unlimited coil, but that will definitely only work with the standard carb.

Okay, thanks for the clarification. I've been reading some on the mtronic and from what I'm seeing the coil and the processor are integrated into one system, is this right? If so is their any way to separate them and relocate the processor then run one of the unlimited coils?

 

[tree monkey]

no

 

[funky sawman]

Its sure funny how more and more folks are having bog issues with the 661. I was the first to post problems with that saw and many did not believe me, ohh well. I do hope the problem gets solved caused I did like the 661 other than the bog

 

[tree monkey]

all ya have to do is find a coil that fits in the hole and make it mount. can't be that hard. I've done more then a few on older saws.

this is going to cost around 2 bills to do

 

[SquareFile]

Brad, once you have it out figured out I'll spot you 30cc. pm me for a address

 

[blsnelling]

Brad, once you have it out figured out I'll spot you 30cc. pm me for a address

Only if you sharpen my chain

 

[Andyshine77]

Cool beans Brad, thanks for sharing your findings! After all that's the real purpose of this forum.

 

[fordf150]

Unlimited coil should be easy. Find one that fits and index the flywheel to match.

Didn't I read that the 660 carb bolts on with no mods?

 

[Big_Wood]

Brad, if you need a coil i have a stihl one that says 1122 on it. think it's 660? if it will fit i can get it out tomorrow. it's a 2 leg kinda thing. i'm real interested in this too. so many fallers ask me to rid them of that m traonic but i've never tried to do it yet. make it way easier if you do it first if everything from a 660 fits the guys will be reall happy as they all have real lots of 660 parts.

 

[big t double]

Doesn't the 660 coil have a timing advance curve to compensate for the flex in the poly flywheel? How would that react working with the aluminum flywheel of the 661....or am I overthinking it?

 

[blsnelling]

My plan was to pull the coil and carb from my 064/066 hybrid tomorrow. If that works, then I will indeed need another coil. I don't currently have a spare one of those on hand. Thanks Shane.

 

[blsnelling]

Doesn't the 660 coil have a timing advance curve to compensate for the flex in the poly flywheel? How would that react working with the aluminum flywheel of the 661....or am I overthinking it?

Good question. I've only seen where one guy on FB claimed that it worked. He didn't show or verify anything though.

 

[fordf150]

261 to 261c conversion is straight forward swap of the carb, coil, flywheel.

 

[Big_Wood]

My plan was to pull the coil and carb from my 064/066 hybrid tomorrow. If that works, then I will indeed need another coil. I don't currently have a spare one of those on hand. Thanks Shane.

no worries. just let me know