New Stihl 440 carb sucks. Does anyone make aftermarket carbs for saws?

[theXman]

Anyone else having problems with new saws not running properly?

I've bought many stihls over the years and loved them, but some of these new ones don't run right.

Two of my newest saws I purchased this summer, a 460 and 440. The 460 runs good all the time, but the 440 is a pain in the ass. My brother also purchased a 440 this year and my workers said they used it and it does the same thing.

Here's what it does:
When you use the saw at 1/2 to 3/4 throttle; lets say to finish the last inch of a cut, or say to cut off a small diameter limb; when you let off the throttle after the cut, the saw dies. Then to start it again you have to usually use choke to pull gas into the carb to get it running.

This is the only time it dies. It idles fine, revs up fine, good power, good high speed. But it's just when you use it at about 3/4 throttle, the thing seems to get too lean and when you get off the trigger it dies, and dies fast. Even if you hear it dying you can't save it by pumping the throttle again.

Adjusting the high and low speed mixture screws doesn't stop this problem.

I've been meaning to take this saw back under warranty since the first day I got it. I figured it would have a year warranty easy. Well, I finally took it in on a rainy day. It's only covered for 3 months for commercial use, and it's been about 4.

Since I believed the mechanic wouldn't find anything "wrong" with it and it wouldn't be covered I didn't leave it with them. I think the new carborator just doesn't run good due to the changes they have to make for emmision requirements.

The only thing I can think that could be wrong, other than design, is that maybe it has a vacume leak if the carb isn't sealed to the cylinder correctly. I doubt this, because it has done this since the first day we got it. But maybe it wasn't assembled right.

I also hate how one of my 200Ts doesn't have a high speed adjustment screw on it's carb.

My first 044 was used just about every day of work (5 day workweek, about 10 months a year) for about 11 years. And was a wonderful saw. This new one has been a pain since the first day of work. I bet my workers waste an hour total in a day from starting it so much. Everyone hates to use it.

Does any company sell aftermarket performance carborators for stihl saws, like for the 440??? Or anyone have old 044 carbs?

Thank you,

--------------------
X

 

[scottr]

EPA Carb

X , a recent thread http://www.arboristsite.com/showthread.php?t=25584 might help .

 

[bvaught]

I have a new 440 (bought earlier this year) and I never experience the problems you describe.

 

[jokers]

Here's what it does:
When you use the saw at 1/2 to 3/4 throttle; lets say to finish the last inch of a cut, or say to cut off a small diameter limb; when you let off the throttle after the cut, the saw dies. Then to start it again you have to usually use choke to pull gas into the carb to get it running.

This is the only time it dies. It idles fine, revs up fine, good power, good high speed. But it's just when you use it at about 3/4 throttle, the thing seems to get too lean and when you get off the trigger it dies, and dies fast. Even if you hear it dying you can't save it by pumping the throttle again.

X

X, It`s obvious that you know what the problem is, the saw is running too lean at partial throttle, an area where the saw was not made to run.

Adjusting the high and low speed mixture screws doesn't stop this problem

That`s right, because you are neither on the lo speed or high speed circuit at partial throttle.

My brother also purchased a 440 this year and my workers said they used it and it does the same thing.

Sounds like your employees all learned how to operate a saw from the same person.

Why does you 440 do this and not your 460? Just an intrinsic difference in the models.

Russ

 

[cunrya]

Just got one last week, got about 10 hr's or so one it now and no pboblems like this yet. However the thing can be a pain to start when its warm, have to go through the whole choking process every time, so there may well be a design flaw in the carb.

 

[ross_scott]

I use the MS440 just about every day for thinning to waste out in the forest or bucking logs to firewood when doing jobs for other people and have never had this issue try geting the carb tuned. Also did you have it retuned after the first 10 hours of use after purchase? this is usually recommended over here by all the chainsaw dealers

 

[Lakeside53]

we sell lots of these... no problems. Take it back... You dealer may be flexible..

 

[bvaught]

Just got one last week, got about 10 hr's or so one it now and no pboblems like this yet. However the thing can be a pain to start when its warm, have to go through the whole choking process every time, so there may well be a design flaw in the carb.

Nope, its not a design flaw in the carb.

 

[stihltech]

fix it

Now this riles me. "I have been meaning to take it back".

TAKE IT BACK. You have a warranty, use it. I cannot fix a saw as it is riding around in the truck. Just like a could not fix a car as it is going down the road.
The saw doesn't run quite right, but you won't even give the dealer a chance to fix it. The magic wand won't work over the phone, sorry.

Customer to customer at counter" I cut umpteen thousand board feet of logs this year".

Brings saw back to shop, tells me, "I don't know why that is wore out, I have used the saw that much". Yes, he has 1 saw.

OK, I feel better now. I will get of the soap box.

 

[DanManofStihl]

I had the same problem on my ms 440 I adjusted out the low screw and haven't had it since it is a fine line on that carb to be to much and not enough. I like ms 066 mags carb better.

 

[theXman]

scottr: Thanks for the old link.
Others: Good to hear most of you have no problems.
Joker: [the saw is running too lean at partial throttle, an area where the saw was not made to run.
QUOTE] Whatever.......... Oh, the saw is meant to either run at idle or top RPM only?! You tell me when you are finishing a cut you are screaming full RPM, or if you cut off a tiny 1" diam limb you hold the throttle wide open? A carburetor is meant to regulate the appropriate gas and air mixture from idle up to top RPM. Maybe your saws should go from a closed butterfly to instant open when you touch your throttle.
[/Sounds like your employees all learned how to operate a saw from the same person.

QUOTE] Wow, maybe I don't know how to run a saw. Lets see..... I've been using saws for 19 years now. I've owned and still have most of these 011, 028,029,020, 200T, 200T, 044, MS440, 046, MS460 and 066. This is the only saw, (besides the 029) that I've had any significant problem with. But yeah, maybe your right, I just don't know how to use a saw.............

Dan: Good to hear that, maybe I'll do extremely fine adjustment to see if gets better. We slow down more toward the fall and I will have some time soon to play with it. I do want to see if there is any vac. leak too.

Stihl tech: Glad you feel better now. My dealer is 18-20 minutes away. If you spent a day with me, you'd see how busy my life is. Besides, I really figured it would be a year warranty and thought I had plenty of time. I have never taken a saw in for anything. We don't just let the 440 sit, we do use it every day, but it is a pain in ass and the 460 getts grabbed if it's not being used. We generally need the 440 and 460 on the crew for each job and I didn't want to do without it, even though it acts up, until things slowed down.

 

[jokers]

Joker: [the saw is running too lean at partial throttle, an area where the saw was not made to run.
QUOTE] Whatever.......... Oh, the saw is meant to either run at idle or top RPM only?! You tell me when you are finishing a cut you are screaming full RPM, or if you cut off a tiny 1" diam limb you hold the throttle wide open? A carburetor is meant to regulate the appropriate gas and air mixture from idle up to top RPM. Maybe your saws should go from a closed butterfly to instant open when you touch your throttle.

Well Xman, maybe it isn`t "whatever". Maybe you don`t know squat about how a diaphragm carburetor on a chainsaw works, but since you are so intelligent and experienced in the world of saws, why don`t you do a little research? Then explain to me how the fuel/air ratio is metered at partial throttle.

Sounds like your employees all learned how to operate a saw from the same person.

Wow, maybe I don't know how to run a saw. Lets see..... I've been using saws for 19 years now. I've owned and still have most of these 011, 028,029,020, 200T, 200T, 044, MS440, 046, MS460 and 066. This is the only saw, (besides the 029) that I've had any significant problem with. But yeah, maybe your right, I just don't know how to use a saw............. .

Well Xman, my statement wasn`t originally intended as a dig at you, how would I know that you are the guy who taught them the wrong way to operate a saw? Apparently it was just a lucky guess on my part.

I don`t care if you have a hundred saws that you`ve owned for a hundred years, you`re a classic example of a know it all who could never learn anything anyway.

Russ

 

[DanManofStihl]

Dang I think you need to calm down jokers maybe everone is not as knowledgeable as you. Ya now come back with an age joke now. I know you are waiting for a chance to belittle some one else. Xman I thought mine might have a vac leak so I installed a new carb kit and that didn't help I sat down with it for 15 minutes and played with the carb. The problem I had was it only did it every now and again so it took acouple of tryes to get it correct. It is a fine setting with the low and the idle speed to get it correct.

 

[stihltech]

fix it

Too busy. I hear it all the time. No excuse. Get it fixed.

 

[West Texas]

We had a problem with an 044 like that. And we tore the carb apart, blew it out with an air hose, put in a 'rebuild' kit with all new gaskets, needle, spring, etc. And made sure the lever was adjusted properly. Put it back together and it has not been a problem since. What was wrong? We don't really know; but, that solved the problem. I'd hate to think this was needed on a new saw; but, if the fine tuning of the "L" jet does not work as Dan suggested, then what the heck, give it a try.

 

[jokers]

Dang I think you need to calm down jokers maybe everone is not as knowledgeable as you. Ya now come back with an age joke now. I know you are waiting for a chance to belittle some one else.

Oh DMOS, my comments had nothing to do with age and they weren`t belittling until xman came back like a know it all because he`s "been using saws for 19 years now'' so he must intuitively know everything. I tried to offer him a valid solution to his problem that will not only resolve the immediate issue, but it will also make his investment(saws) pay out better. Do you have a problem with that? Xman is free to take my suggestion or leave it, but if he comes back with statements trying to make me look like the fool, he`d better be able to back them up.

I`m not saying that I`m going anywhere or that I`m the only guy who knows anything or has a good idea, but how would you like it if everyone who knows anything just up and left here, which left you to spout off anything you like? Then this site would be no better than the Tool Shed which in my opinion isn`t worth reading.

I could go on DMOS but this isn`t about you, but I did think you were getting better. Dang, I was wrong again.

Russ

 

[theXman]

Joker, I thought your original response was written in a "ignorant" tone. Maybe you didn't intend it that way. Sorry if I read it wrong. Or, if you did mean it that way, so what.

But, being serious now. Maybe a don't know exactly how a diaphragm carburetor on a chainsaw works. And lets say I don't know how to run a saw correctly. Why have I never had a problem with a saw doing this before??? Is it just now that this new 440 finally has a touchy carburetor that shows my faults? And everyone around me doesn't use this saw right either?

I'm truely being serious here and not interested in continuing to throw around insulting statements. At least, not right now.

 

[TimberPig]

The biggest problem from the sounds of it is the carb is not correctly adjusted. Modern saws are choked up in the muffler and lean in the carb settings. They also are not designed to meter fuel properly at partial throttle settings, which means they are running lean if they are run at partial throttle. Lean adjustments on the high and low circuits will only make this worse. A proper carb adjustment will go a long way towards resolving the issues you are experiencing.
As to the issue of only running it wide open or at idle, for cutting small material, rather than partial throttle operation, try a burst of throttle as you cut through it, then let off once you are through the piece.

 

[Diesel JD]

All of the manuals tell you to always run the saw at full RPM, I don't run mine that way. I didn't know about the saw running lean at mid throttle....the point is these guys are correct on the "right" way to run a saw, but I doubt if most saws are run that way in the actual work environment. If the MS440 were mine I'm pretty sure I'd have taken it back to the dealer...but since you are out of warranty, that clouds the issue a bit more....

 

[jokers]

Joker, I thought your original response was written in a "ignorant" tone. Maybe you didn't intend it that way. Sorry if I read it wrong.

OK, we`ll call it water over the dam and I apologize for my response to you.

Why is this happening to you now when it never happened before? Could be a few reasons as a several have pointed out. Perhaps the passages or nozzles in the new carbs are smaller or maybe the anti bleedback valve takes more effort to overcome. Maybe your inlet lever is set too low. The fact that this occurs on two new 440s that are operated this way suggests a change made to the new saws. At any rate, you sure seem to be running lean and you wouldn`t notice it in output power in a small limb or as you feather a cut.

Now for running the saw WFO, yeah that`s true. Just blip the throttle as you limb but blip it good. When making a big cut, finish with the throttle pinned, releasing the throttle as soon as you bust through, you won`t hurt the saw, you`ll be helping it.

Russ