Stihl MS 661 having the bog blues

[funky sawman]

Here we go with an update today. I was doing a thinning and pruning job today and I needed the longer length of the 32" 661 to reach some large grand fir limbs. When the saw is running full throttle while the bar is pointed to the sky it runs really rich, four stroken like crazy, then when bar is horizontal it revs a lot higher. Still sounds like a carb issue to me.

 

[Derrick Sawyer]

Sorry I can't help with Mtronic since I sold all the ones I briefly had (too new for me), but my 044 was having a similar issue as I think your 385 where after a long cut, the idle would drop too low and die, dropping to 2200 rpm, versus normal idle around 2600-2800, so if I set idle at 3000, it will still stay running when it drops idle but still very annoying, and once in while the idle would drop on its own. Tried to clean out the C3M carb and new carb kit but didn't fix, so swapped in another carb and that fixed it. Probably is the carb in your case, but just curious if the same intake adaptors work to do pressure/vac testing on the new saws as the with the older ones, and if a seal leak on a regular saw can appear as in increase in WOT RPM with saw tilted to one side, would an Mtronic try to adjust for this and then run like crap but not run too lean (thinking like the opposite of intellicarb, that would lean mix due to clogged air filter)

 

[MustangMike]

Almost sounds like an air leak problem. There is no other reason I can think of that the saw would run different when pointed up, unless something is wrong with your fuel delivery.

Did you change fuel filter, fuel line & plug just to rule the simple stuff out? If so, I think I would vac test it next.

 

[Locust Cutter]

This partially sounds like a kinked fuel line, similar to some recent Huskys... BUT, changing position sounds very much like a crankcase leak...

 

[Moparmyway]

Here we go with an update today. I was doing a thinning and pruning job today and I needed the longer length of the 32" 661 to reach some large grand fir limbs. When the saw is running full throttle while the bar is pointed to the sky it runs really rich, four stroken like crazy, then when bar is horizontal it revs a lot higher. Still sounds like a carb issue to me.

I will try this with mine.
I should be firing her up this weekend and will report back to you asap

 

[the GOAT]

My 362 C ran great all day today .....

Awesome!!!

 

[Robin Wood]

This partially sounds like a kinked fuel line, similar to some recent Huskys... BUT, changing position sounds very much like a crankcase leak...

thought the same since OP's 1st few posts, gotta suck if its crankcase leak
even if it does hope he gets away with bad crank seals

 

[redbull660]

muffler on it's way! hope they fix your saw fast man.

 

[funky sawman]

Thanks to redbull660 my saw is now at the dealer getting warranty work. Lets see what happens...

 

[CR888]

Redbull a good guy. l think he is Stihls biggest single customer. lf he decided to run husky, they'd be in trouble for sure. lts interesting how the op says after a long cut if he switches to limbing the throttle response falls on its face, it sorta seems like its stihl tuned rich from the long cut and is not recalibrating itself quick enough. Redbull will get it sorted for ya, otherwise he'll have Andreas on the phone.

 

[funky sawman]

I hope my dealer can figure it out, he told me they did not have the diagnostic software to plug the saw into cause it costs like 800 dollars.

 

[funky sawman]

meanwhile my little 241cm is running like a dream, even trying to cut the big stuff that I would be normally using the 661 on

 

[funky sawman]

I will say this, if the 362cm is anything like the 241, it would be one heck of a saw....realy starting to have early buyers remorse, but then again I gotta give the dealer a chance to figure this saw out before I give up on it.

 

[AKDoug]

I hope my dealer can figure it out, he told me they did not have the diagnostic software to plug the saw into cause it costs like 800 dollars.

You can test everything without the software. On the flip side, I own the software and have never needed it yet

 

[Wood Doctor]

Rather interesting that I have rebuilt three MS660 saws and one 066 that were all down one way or the other from either accidents or abuse, but all of them now run fine today. Not one displays the symptoms described in this thread and the 066 has to be 15 years old. I have to be hesitant about the MS661.

 

[redbull660]

Rather interesting that I have rebuilt three MS660 saws and one 066 that were all down one way or the other from either accidents or abuse, but all of them now run fine today. Not one displays the symptoms described in this thread and the 066 has to be 15 years old. I have to be hesitant about the MS661.

I'll sell you my mint 660R i used for some of my tests.

 

[nk14zp]

A 395xp will cure all your bogging troubles.

 

[MustangMike]

I ran a 661 at GTG today, very impressed.

 

[Wood Doctor]

I'll sell you my mint 660R i used for some of my tests.

That would indeed be interesting provided any one of the four decides to conk out. Trouble is, these saws love to run and the loggers using them have good experience with them. So, they rarely fail. Occasionally a big log gets loose and rolls over one of them. They have even survived that with a new tank housing and chain brake handle.

Right now these saws are all keepers and three of them are pulling 36" bars for big cottonwoods. Regardless, RedBull, I'll file your offer away and holler as needed. I'm going to be heading north to Danbury, WI early next month. How far are you away from that path? Might be worth a PM.

 

[Moparmyway]

How much are you sellin it for ?