Stihl 041 Rebuilt - Running too rich

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Touch MM leads together before test to get a true 0 reading.
Might be .2-.3 ohms due to lead resistance.
A good MM will have an adjust screw center of unit below pivot of needle. That's on a galvanic response meter. If it's digital, there should be a zero button which you press while holding the leads together. Touch leads together and adjust to ZERO if yours has the adjustment screw, or press the zero button. Also, low batteries will cause a bad reading. OT
 

Patrick1903

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This should help, I did this video a while ago. To get the condenser out you need to remove the stator and tap it out from the front by pushing in the back of it. It’s just a press fit.

As for grease, it depends how much it’s used. For home owner use, each service - generally yearly.


Wow, great tutorial. Thanks for taking the time to make that video and sharing it.
 

Patrick1903

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The ATOM CDI Module you have is mounted it the worst possible location, perhaps other than on the muffler.

Those modules with not take the heat that is coming from the cylinder head. You should move it to some spot that will not heat it up.

As far as the flooding goes, I'm guessing that as the heat from the engine heats up the fuel and air in the fuel tank, the pressure created forces fuel into the carb, over-powering the needle and flooding the engine.
@Jondoe @Vintage Engine Repairs said the same thing regarding the location of the module. The fact that the screw was touching the cylinder head really couldn't have helped. I do not know if the saw ran that way with the original Stihl cylinder (which I still have, and appears to be in good condition).

I am wondering if the flooding is a red-herring. Perhaps the ignition would fail, then I would continue to crank the saw with an overheated module, and then the plug would foul? It's hard to tell... appreciate your hypothesis and hope to get the saw running again long enough to heat it up and see if it will die agian.
 

Patrick1903

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Good morning all. :)
I have read this entire thread. A lot of things have been done and great suggestions made by VER. Earlier in the thread you mentioned that it has tremendous vibration due to a bent crank shaft. Just wondering why nobody has suggested replacing the crank shaft? The vibration is pretty bad as you had to stop and tighten the top cowl screw several times while sawing in the video. I feel that nothing will work properly with that much vibration. Vibration at high speed = resonance or harmonics. That alone can effect the operation of the carburetor not to mention the operation of the points. Maybe that is why someone went to the CDI?
The bent crank - perhaps I had glossed over that and not really spent enough time looking at that. (Wishful thinking on my part, hoping it wasn't really bent? :) But you are absolutely right - if that is causing an amount of vibration that is really adversely affecting the rest of the saw's operation, then nothing else is really worth doing. I was hoping the vibration was more of an annoyance, but if the air filter cover won't stay on under power - then that doesn't make for a very useful (or fun) saw. I will try to get a picture or measurement of where I was seeing the "out of round" on the clutch side. My initial thought regarding replacing the crank - that may be a showstopper. On second thought, (depending on cost), I suppose it would continue to be a good learning tool for me. It's been great so far, and am really thankful for everyone's input/ideas/advice.
My second concern is what caused the original damage to the piston with the welded ring? Running to lean and overheated maybe? Straight fuel with no mix maybe? Foreign matter entering the intake? Something had to cause that. I'm just curious. These are just thoughts that entered my mind while reading the thread. Keep us posted. I really enjoyed reading your progress.
I can't remember if I posted this on this thread - I think it's buried somewhere here, but when I picked up the dead saw there was some missing hardware on the exhaust. One of the screws into the cylinder at the exhaust port was 1/4 way backed out. The exhaust would have been slapping into the exhaust port. And according to my father in law - he hadn't taken anything apart after the saw died (that he remembered). So it seems that something could have easily been ingested into the cylinder. Just a guess. I seriously doubt it was straight gassed, because we run a fleet of saws (meaning 5) and fuel them from the same "mix" jug when we're doing tree work. Not to say it's impossible, but I would think unlikely given our setup and keeping all the saw tools/fuel together.
And Patrick, your probably snowed and iced in like we are here in KY. :cool: Have a great weekend. OT
No snow this time for us. All rain yesterday and today. Temp is reading 63 degrees F this morning - pretty wild! We've been having teens to twenties most mornings in the past couple weeks. Wild weather. Have a great weekend too, thanks for finding the thread!
 

cbfarmall

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Isn't the 041 susceptible to the same oil pump issues as the 051s and 075s? There is a boot/collar around the pump inlet/outlet that seals the ports. This fails and bar oil ends up in the case. Could also become an air leak. Pull the pump straight out the front of the case to replace it.
 

Patrick1903

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Isn't the 041 susceptible to the same oil pump issues as the 051s and 075s? There is a boot/collar around the pump inlet/outlet that seals the ports. This fails and bar oil ends up in the case. Could also become an air leak. Pull the pump straight out the front of the case to replace it.
Hmm...so do you think that could be at play here? Or basically it's at play in any 041 if you don't check/replace those seals??

For reference regarading oil pump -
1643985627078.png
1643985697002.png
 

cbfarmall

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I didn't watch the videos but you keep describing an oily mess in the cylinder. Part 6 is what I was referring to. For a bent crank, pull the plug and clutch cover, pull it over and watch for runout. Besides, these saws are well known for their vibration.
 

cbfarmall

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Hmm...so do you think that could be at play here? Or basically it's at play in any 041 if you don't check/replace those seals??

For reference regarading oil pump -
View attachment 962113
View attachment 962115
Nevermind, I watched the video. Bar oil in the cylinder would smoke like a freight train. Your problem definitely sounds like ignition. And also too lean, but until you straighten the ignition out, that issue remains clouded.
 

Patrick1903

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Nevermind, I watched the video. Bar oil in the cylinder would smoke like a freight train. Your problem definitely sounds like ignition. And also too lean, but until you straighten the ignition out, that issue remains clouded.
OK thanks. I'm curious about checking the oiler, but maybe I'll do that if I can sort the ignition out so as to not throw too many variables into the mix. I'm afraid I would introduce a problem getting into the oiler, so want to keep that from happening until other things are ok.

Still - the other issue as you mentioned, is the runout. But we'll see about the ignition first before figuring out what (if anything) I do about the crank.
 

Patrick1903

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Stop guessing... Just check the crank (both ends) with a dial indicator. That way you will know if you have an issue or not!
Hi Steve, I don’t have a dial indicator. I’ll have to see about getting one to measure the runout. It’s only on the clutch side, not the flywheel side. Flywheel side was fine judging by how little tolerance there is between the flywheel and case, and just by looking at it.
 

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If I understand what changes you have made, you have replaced the piston. Did you weigh the new piston to make sure that it is the same weight as the old one ? If the weight is different, that would explain the vibration. The piston, rod and crank have to be a balanced assy.
 

Patrick1903

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If I understand what changes you have made, you have replaced the piston. Did you weigh the new piston to make sure that it is the same weight as the old one ? If the weight is different, that would explain the vibration. The piston, rod and crank have to be a balanced assy.
I did not weigh the piston. I think there was vibration in the saw before the new top end, due to the hardware that was either missing or loose. Not to say that adding an imbalance wouldn’t exacerbate things after the new piston/cylinder.
 
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I didn't watch the videos but you keep describing an oily mess in the cylinder. Part 6 is what I was referring to. For a bent crank, pull the plug and clutch cover, pull it over and watch for runout. Besides, these saws are well known for their vibration.
With all due respect CB, all saws vibrate. Even the AV models. But not like the vibration he is experiencing. It is bad enough on his, that he has to keep tightening the top cowl/filter cover screw while using. Just saying. OT
 

cbfarmall

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With all due respect CB, all saws vibrate. Even the AV models. But not like the vibration he is experiencing. It is bad enough on his, that he has to keep tightening the top cowl/filter cover screw while using. Just saying. OT
I have a 'few' saws so I'm aware they vibrate, some more than others. Worns threads can cause the filter to come loose repeatedly. That said, I am not saying the crank is or is not bent. Not enough information. Maybe the clutch shucked a lining or the fanwheel has a bunch of broken fins. A couple quick visual checks would probably answer all questions.
 

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I’m in the process of putting new points on the stator plate. I was really not understanding how it was possible to get a feeler gauge under the flywheel and to figure out how I could adjust the slight movement of the points without seeing them. Then I realized those screws on top of the flywheel can actually be removed to take off the “flywheel fan” (forgetting the exact name right now). So that makes me a whole lot more sense now! I also learned from the service manual for 041FB that they’re called cheese head screws. I see them all the time but never knew. The service manual is really written in a way that is helpful and can teach the reader a lot, besides just providing steps to perform a task.
So question on points: I am not looking at the manual right now, but I think the gist of the procedure is to move the flywheel until you are at TDC (marked on flywheel and on crankcase). I think I found the correct mark on the crankcase. However, it seems like I have to go several degrees past there for me to see the cylinder stop moving upwards. Does any of that matter or do I just want to know when the cam on the flywheel opens the points to their max opening. Then move the points in or out to get to the correct gap?
see pic of index point on crankcase (I think.). Is this what that is? 2nd pic shows where TDC appears for me when looking through the exhaust/intake ports. Keep in mind I put a new aftermarket P/C (same size as oem) in the saw, but not sure if that could account for a difference from when the index was made.
Last picture Removed flywheel fan (aha!) (and don’t mind the clutch…I didn’t have that installed in the fan…)
 

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Jondoe

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Patrick, it looks like you are working on your saw engine in your kitchen. How is that going over with your wife ?​


Typically you would adjust the points to open just before TDC. So what you are seeing as far as the timing marks on the flywheel and case sounds about right. You need to adjust the points so that they open as the flywheel marks line up.

Turn the crank in the opposite direction or normal rotation some so that the cam on the flywheel is not touching the rubbing arm on the points, and then slowly rotate in the normal directing and watch when the points open. They should open just as the timing mark on the flywheel aliens with the mark on the case.

You can use your ohm meter or just a small battery and a light bulb to help identify when the points open.
 

Patrick1903

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Patrick, it looks like you are working on your saw engine in your kitchen. How is that going over with your wife ?​

Ha! That’s our basement, a kitchen of sorts down there. Much better than working in the freezing garage. I will occasionally have a carb on our kitchen counter. The under cabinet lights are bright. I need to work on my garage setup.
Typically you would adjust the points to open just before TDC. So what you are seeing as far as the timing marks on the flywheel and case sounds about right. You need to adjust the points so that they open as the flywheel marks line up.

Turn the crank in the opposite direction or normal rotation some so that the cam on the flywheel is not touching the rubbing arm on the points, and then slowly rotate in the normal directing and watch when the points open. They should open just as the timing mark on the flywheel aliens with the mark on the case.

You can use your ohm meter or just a small battery and a light bulb to help identify when the points open.
Great, thanks for that. So when it starts to open, I will keep the cam in that spot and move the points to get the right gap, then tighten it down? Or do I need to keep rotating until the cam is at the apex, then adjust the gap? Sorry, I’m having a hard time envisioning this…
 

Jondoe

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I was not aware that you can move the points. That is somewhat unusual.

Do you have a spec for the point gap ?

I see the points in your post #31. The point location is fixed by the post that it fits over. The small screw on the left of the points in that photo is what you use to adjust the points. It only allows you to rotate the points around the post. I see from the photo that there is a very small adjustment area as the points have a little bracket that fits into a slot limiting the movement.

With the flywheel in place and secured, aline the timing mark on the flywheel with the mark on the case. Loosen the small screw and rotate the points around the pivot until that points just start to open. Then tighten down the screw. Done !

By connecting a 1.5 volt battery and a bulb in series across the points, the bulb will help you see when the points open as the bulb will go out.

I see that they have provided a dust cover for the points. You should put that back on after adjusting the points.
 

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