MS 661c cylinder issue

[Yukon Stihl]

Personally I run 32:1 mix with good oil.
Most Porters will recommend that for their saws

 

[Maintenance supervisor]

That cylnder looks straight gassed to me, but anything is possible.

 

[seancpr1985]

From the parts i see on their website it uses the bar oil pump to provide lubrication for the drive chain since the bar adapters are slotted for the oiler. You'd still need oil even if the attachment didn't because you'd kill the oil pump unless you took the pump out.

I guess it doesn’t say NOT to use bar oil, but from reading this it says you need to use chain lube on the attachment drive chain. Which I guess I just assumed it wasn’t able to be lubed via the bar oil port. Maybe I’m wrong.

 

[seancpr1985]

Could also run a larger drive sprocket to bring the rpm down a little. But it looks like there’s an air leak that the mtronic can’t compensate for or the mtronic just isn’t putting out enough fuel.
What’s the number on the coil? I’m guessing it’s running the white solenoid?

Here is cool. What solenoid are you referring to? The part on the side of the carb?

 

[seancpr1985]

From the parts i see on their website it uses the bar oil pump to provide lubrication for the drive chain since the bar adapters are slotted for the oiler. You'd still need oil even if the attachment didn't because you'd kill the oil pump unless you took the pump out.

This is what it looks like attached to machine, and then one without it. It doesn’t look like it uses the oiling port. Also if I remember correctly the one time someone added bar oil, to the old machine not this one, it just made a huge mess.

 

[BradSt]

Here is cool. What solenoid are you referring to? The part on the side of the carb?

Thats the newest coil/module. The earlier 4700 coils had potential "lean" issues, even though most never had an issue with them.

Would be interesting to see the readout from that 4702 module on runtime data, to see how the engine was used. Need the Stihl diagnostic tool to see that though.

Also, have any pics of the top and underside of the piston?

 

[seancpr1985]

Thats the newest coil/module. The earlier 4700 coils had potential "lean" issues, even though most never had an issue with them.

Would be interesting to see the readout from that 4702 module on runtime data, to see how the engine was used. Need the Stihl diagnostic tool to see that though.

Also, have any pics of the top and underside of the piston?

The diagnostic tool would plug into the side of the carb? That would be interesting to know. Maybe I can get a holding one of those. Here are pics of piston.

 

[huskihl]

Here is cool. What solenoid are you referring to? The part on the side of the carb?

Yes

 

[Maintenance supervisor]

I'm just gonna throw this out there,
Why not buy a 4 set of clone 660s and let the chuckle heads destroy them?
Even if your having to buy state vendor price they have to beat it by a certain amount (which they won't) so instead of turning a high quality wood cutting machine into a trencher you could buy 4 clone 660s and make it through a whole season with out pissin¡ 1300.00 out the window.
Just a option, and I understand any reluctance to this suggestion/subject.

 

[seancpr1985]

I'm just gonna throw this out there,
Why not buy a 4 set of clone 660s and let the chuckle heads destroy them?
Even if your having to buy state vendor price they have to beat it by a certain amount (which they won't) so instead of turning a high quality wood cutting machine into a trencher you could buy 4 clone 660s and make it through a whole season with out pissin¡ 1300.00 out the window.
Just a option, and I understand any reluctance to this suggestion/subject.

Sorry for my cluelessness, but when you say “clones” what are you referring to? Another manufacturer with the same specs? I have already ordered new cylinder kit.
What is a good clone? I have no reluctance. I am open to all opinions and suggestions.
These chuckleheads could screw up a wet dream. So I need all the help I can get.

 

[J D]

instead of turning a high quality wood cutting machine into a trencher you could buy 4 clone 660s and make it through a whole season with out pissin¡ 1300.00 out the window.

+1 for that idea.
Given past experience, you'll probably find you get about the same life out of em anyways... The traditional carb will lend itself better to your application. You can afford to loose a bit of power so tune rich & run extra oil. Leave the bar oiler out from the get go & by the time they've blown 3 or 4 up you'll probably be able to resurrect one out of the bits.
He's referring to the Farmertec/Huztl clones

 

[seancpr1985]

+1 for that idea.
Given past experience, you'll probably find you get about the same life out of em anyways... The traditional carb will lend itself better to your application. You can afford to loose a bit of power so tune rich & run extra oil. Leave the bar oiler out from the get go & by the time they've blown 3 or 4 up you'll probably be able to resurrect one out of the bits.
He's referring to the Farmertec/Huztl clones

Ok thanks. I will have to see if those brands are available from our suppliers, as I am only available to buy from certain places under state contract. But I’ll look into it for sure.

 

[Maintenance supervisor]

Sorry for my cluelessness, but when you say “clones” what are you referring to? Another manufacturer with the same specs? I have already ordered new cylinder kit.
What is a good clone? I have no reluctance. I am open to all opinions and suggestions.
These chuckleheads could screw up a wet dream. So I need all the help I can get.

I sent you a link.

 

[Maintenance supervisor]

Ok thanks. I will have to see if those brands are available from our suppliers, as I am only available to buy from certain places under state contract. But I’ll look into it for sure.

State contract has its limitations, in my state if you can beat the price by 30% with a similar product your good to go. Check the contract and dont get into trouble, absolutely nothing will get you sh¡t canned faster than misuse of procurement card or state funds.

 

[FamilyTradition]

Good morning all. I appreciate the thread and am fascinated. I understand the saw will pull/run the attachment, but my question is, is it really the right tool for the job? What task is being performed that necessitates the use of this system? Is clearance in the field an issue? Trees, rocks, residential/commercial structures? Other adjacent utilities? Residential homeowners worried about damage to their lawn? I work with a municipality in Virginia as their insurance broker. From a CBA, Cost Benefit Analysis, these failures would have me seeking other options. Just a thought, not being argumentative. What say y'all? Max.

 

[seancpr1985]

Good morning all. I appreciate the thread and am fascinated. I understand the saw will pull/run the attachment, but my question is, is it really the right tool for the job? What task is being performed that necessitates the use of this system? Is clearance in the field an issue? Trees, rocks, residential/commercial structures? Other adjacent utilities? Residential homeowners worried about damage to their lawn? I work with a municipality in Virginia as their insurance broker. From a CBA, Cost Benefit Analysis, these failures would have me seeking other options. Just a thought, not being argumentative. What say y'all? Max.

I may need a stronger power head. But like a said before, it is the one that was sold to us from the company that makes the trenching system. Also prior to the first failure. It was used off and on for a few years with no issues at all. All we use it for is trenching through the earth for irrigation lines. It is never used for cutting. We don’t even have a bar for it. But since it’s first failure it’s just been an ongoing issue since. How much bigger do saws get than the 661 we have? Seems pretty large and powerful do they get much bigger?

 

[Yukon Stihl]

The MS881 is out now if you want to stay with Stihl's.Not cheap though.

 

[seancpr1985]

The MS881 is out now if you want to stay with Stihl's.Not cheap though.

Well I have the cylinder repair kit already. When I get back from vacation I will be installing it. But thank you for this recommendation. If the problem happens again, I’m going to have to probably go this route. And yes I would prefer to stay with Stihl if possible.

 

[J D]

Well I have the cylinder repair kit already. When I get back from vacation I will be installing it. But thank you for this recommendation. If the problem happens again, I’m going to have to probably go this route. And yes I would prefer to stay with Stihl if possible.

From what you've previously said I don't think a bigger saw is going to be a solution. It will likely end up being run at part throttle even more leading to further problems. If they now match it to a 462 I would look for something similar. My pick would be a 460, with a traditional carb you can tune it a bit rich & you're less likely to have part throttle issues. Make sure fuel is FRESHLY mixed with at least 40:1 quality synthetic oil.
When you rebuild your 661 be sure to pressure/vac test it! I strongly suspect your previous issues were the consequences of previous lean &/or low oil running