Stihl 041 Rebuilt - Running too rich

[Patrick1903]

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.

.4mm. Take a look at page 36 of 66 in the manual here. Scroll down til you see the reader window. You can zoom in on the text.

https://chainsaw-workshop-manual.com/product/stihl-041-farm-boss-service-workshop-manual/

 

[Oletrapper]

Somewhere in my arsenal of tools, I have a set of what I call crankshaft collars. They emulate the actual flywheel center that contacts the points wiper.
They are ancient. There was a time when there were no openings to allow for point gap adjustment. These "collars" had to be used. I'll have to look for them. lol OT

 

[Patrick1903]

Somewhere in my arsenal of tools, I have a set of what I call crankshaft collars. They emulate the actual flywheel center that contacts the points wiper.
They are ancient. There was a time when there were no openings to allow for point gap adjustment. These "collars" had to be used. I'll have to look for them. lol OT

That’s what Stihl must be calling the “special adjusting cam p/n 1110 893 0500” on page 36/66 of that link in my last post.
I’m hoping this is just one of those things you have to do once and then the lightbulb will go off. I think fundamentally my question is - the points will begin to open (interrupt the continuity on a multimeter) but I may still have to keep rotating flywheel to get to the “apex” of the cam lobe. The manual says that when at TDC it opens the breaker “fully.” So I think I need to find the max opening, then adjust points to get the 4mm.
1st Picture of points in the closest position to crank and furthest from crank in pic 2. Not a whole lot of adjustment but I guess we’re dealing in really fine measurements.

 

[Vintage Engine Repairs]

Pat, set the piston to TDC and open points to 0.35mm - 0.40mm.

Place a 0.03mm feeler gauge between the points and gently pull on it. Turn the flywheel, as soon as the feeler slips out of the points, see where the alignment / timing marks are.

Adjust the position of the stator plate via loosening the two screws that hold the stator down and turn it one way or the other.

Test again until it’s aligned.

Apply oil and grease to the appropriate contact surfaces and clean the points with acetone and you’re done.

P.S that coil is Chinese not oem stihl.

 

[Jondoe]

Good post. I failed to see the slots for adjusting the rotation of the whole plate.

 

[Patrick1903]

Pat, set the piston to TDC and open points to 0.35mm - 0.40mm.

Place a 0.03mm feeler gauge between the points and gently pull on it. Turn the flywheel, as soon as the feeler slips out of the points, see where the alignment / timing marks are.

Adjust the position of the stator plate via loosening the two screws that hold the stator down and turn it one way or the other.

Test again until it’s aligned.

Apply oil and grease to the appropriate contact surfaces and clean the points with acetone and you’re done.

P.S that coil is Chinese not oem stihl.

@Vintage Engine Repairs - Great, thanks for this. I am confusing myself. I just need to experiment with it based on your instructions and the manual and do it. I was away from it recently - so maybe this week I hope.

When I pulled the flywheel off, my first thought was Wat-yong didn't sound German! Wishful thinking that it was some Honk Kong company that Bosch subcontracted with in the 1970s... So much for buying OEM Bosch points and keeping the saw original! If things are still erratic ignition wise then perhaps I'll try to source a Bosch coil.

 

[Patrick1903]

It’s been awhile since I made progress on the 041FB. I finally got the ignition restored back to the original points and condenser (from the Atom CDI module). Thanks to @Vintage Engine Repairs for some great pointers and recommendations. The saw starts right up. That wasn’t the problem before; it was after 15 mins running it would die really hard. With no restart. Then plug would foul. So I can’t really tell now whether or not the problem is solved until I run the saw in earnest. And I have PHO, so waiting for b&c to arrive via mail (it’s from my families farm, and I don’t get back but every month or two). And I don’t have a b&c here that I can test it with.
So I notice it’s really throwing a lot of smoke. And plug still seemed pretty messy (though again, just idling with some revving, but not much throttle yet). I closed the low speed screw entirely and it still ran. Definitely not we’ll, but and really badly lugged when accelerating. With the normal setting it accelerated normally. I really am looking forward to seeing what happens with bar and chain, and cutting some wood. In the back of my mind I’m still struggling with the carb. With original Tilly on there, it started doing the die, then pull til it floods thing. That was with Atom CDI module. I bought a replacement carb, and same thing happened. But now for some reason I think I should revisit the Tilly carb. Lever too high?? Ahh… so many variables! But at least the new ignition seems viable. That was a first for me. And we’re slightly closer to a vintage saw I suppose!
Another observation. Fuel tank was half full (sorrry Tom, I watched your video too late), but fuel was bubbling out of cap. Is that normal, and why or why not?
please see videos and picture of plug after idling.View attachment trim.423911E4-4480-4AC3-8C99-4F8D3FAF7A3E.MOV

 

[Vintage Engine Repairs]

Hey mate good to hear from you, can’t offer a full in-depth reply just now as I’m about to get on with work, however just a side note. 2 strokes engines are not designed to sit and idle like a 4 stroke can. You’ll get fuel pooling in the crank causing irregular rpm, wet and then carboned up plugs, , ignition issues, exhaust port and spark screen blockages too. I’m going to upload a video shortly that covers the most common tuning mistakes and pitfalls, I cover this is quite a bit of detail. I think you’ll find it useful for your tuning.

 

[Patrick1903]

Hey mate good to hear from you, can’t offer a full in-depth reply just now as I’m about to get on with work, however just a side note. 2 strokes engines are not designed to sit and idle like a 4 stroke can. You’ll get fuel pooling in the crank causing irregular rpm, wet and then carboned up plugs, , ignition issues, exhaust port and spark screen blockages too. I’m going to upload a video shortly that covers the most common tuning mistakes and pitfalls, I cover this is quite a bit of detail. I think you’ll find it useful for your tuning.

Thanks Tom. I forwarded your tuning video to my brothers. Great tutorial. I know it doesn’t like to sit there and idle, especially with no load on the sprocket. So I’m looking forward to getting the bar and chain and putting it into wood. Putting it back to points and (having it start!) is a big win. Baby steps…I do want to revisit the carb situation ( to get the tillotson back on). If I remember, I bought a g&d kit, the new metering diaphragm has the raised part to hook to the lever. Since the diaphragm on the carb didn’t have that, (was just the nub), I only did fuel pump side diaphragm. In hindsight I think I just needed to hook it onto the lever. I had never rebuilt one like that before. All of that is another variable though, and I want to isolate the ignition first, since that is what has been changed. Have a good day at work! And thanks all for following my progress.

 

[Vintage Engine Repairs]

All good mate, I’d safely ignore plug colours for now, all that’s telling you is exactly what it should - it’s not burning fuel efficiently.

It’s running beautifully at idle, maybe slightly rich on L as it’s gradually loading up, but it’s not bad. Those older saws flow air so well that you can run them rich down low with little problem.


We tune the idle on the rich side for good off idle acceleration, but the flip side of this is that when it does idle for long periods or even shorter ones, with just a little throttle blipping you’ll be burning more fuel that what it can fully combust. The result is carbon fouling, wet plugs etc.


Regarding that fuel venting, it’s completely normal. Inside that lid will be a plastic bung and behind that within the plastic cap a small grub screw.

It’s actually a better system than a one way valve as it vents pressure both ways and eliminates what is best described as a geyser .

It’s just telling you there is more pressure in the tank from heat ambient temperature or agitation and it’s venting that out while a bit of fuel is within the threads.

 

[Patrick1903]

OK, bar and chain arrived today. Slapped it on, tried to pull the chain by through hand. It was pulling the engine over. Pulled it off, scratched my head. Thought maybe clutch springs were worn. But unscrewed the clutch and it came off without the shoes catching the clutch drum, as I spun it off. So figured springs may be ok. Started looking at the service manual for thoughts. I notice it says "Now fit the smaller washer on the crankshaft so that the outer diameter of the recess faces the crankcase." Hmm....I didn't have another "washer" after installing the items in the picture from service manual. And I don't really understand what "outer diameter of the recess faces the crankcase" means. I don't recall an outer diameter of anything after the sprocket.

See below what I see after pulling clutch off:


From the service manual, there are 6 items pictured. If numbered from 1-6, left to right, I have 1-4, then 6 (clutch). So I think that would explain why the rim sprocket (on splined clutch drum), won't turn without turning the clutch. The clutch back surface is basically screwed down onto the clutch drum. I believe the "washer", the "pointed" part, will ride against the other washer (item #4 in the picture (from L to R), which is against the needle bearing.


Heres a pic of the washer I am missing (and just ordered).


Also troubling me lately is the condition of the rim sprocket. It appears the oiler pin that goes into the sprocket and the worm gear had broken at some point and was replaced? The pin in there now doesn't appear to be broken on either end. (That I can tell anyway.) So perhaps pin was replaced but still has remnants in the sprocket? It still seems to work this way, but I would like to verify the pin and sprocket setup is correct (i.e. replace the sprocket at least). I was struggling to find the right oregon spur and sprocket combo (figure I'd do both). So maybe will reinvestiage just a sprocket. See pics of that, below.


Oh well, so much for getting to a real trial run with new bar and chain. Time to wait again for more parts! I'm afraid to start calculating costs at this point...

 

[Vintage Engine Repairs]

I don’t imagine they ever came with rim sprockets from the factory, they would have been spur drives. That’s an after market clutch drum and the hole is incorrect. When the previous owner replaced it he used the wrong part.(Oregon rather than stihl). Check the clutch itself says stihl on it while you’re there.

Well done for being so patient. It’s a waiting game - I have been trying to source a pto side crank shaft bearing for 6 months. Finally found one in the Uk!

 

[Woodslasher]

I don’t imagine they ever came with rim sprockets from the factory, they would have been spur drives. That’s an after market clutch drum and the hole is incorrect. When the previous owner replaced it he used the wrong part.(Oregon rather than stihl). Check the clutch itself says stihl on it while you’re there.

Well done for being so patient. It’s a waiting game - I have been trying to source a pto side crank shaft bearing for 6 months. Finally found one in the Uk!

I'm not 100% sure you're correct on that Tom, most of the 056's I've encountered were wearing an Oregon drum and Oregon did offer rim conversion kits even if the manufacturer didn't. A quick search says the drum is correct for the drum and I'm not entirely convinced that the hole is incorrect. Also, I see a Stihl p/n cast in to the clutch so I suspect it's legit.

 

[Patrick1903]

A quick search says the drum is correct for the drum and I'm not entirely convinced that the hole is incorrect. Also, I see a Stihl p/n cast in to the clutch so I suspect it's legit.

Thanks. I have seen the same Oregon PN 18200 that I have, though more of the 18200X version that you showed. The 18200 appears to have the pin hole for the oiler pin, where the 18200x doesn’t. See pic. Also note that mine appears broken. If you look close at my earlier pick, I think you can see what appears to be a remnant from a pin in there. Does anyone see that too?
Oregon 18200.

 

[Woodslasher]

Thanks. I have seen the same Oregon PN 18200 that I have, though more of the 18200X version that you showed. The 18200 appears to have the pin hole for the oiler pin, where the 18200x doesn’t. See pic. Also note that mine appears broken. If you look close at my earlier pick, I think you can see what appears to be a remnant from a pin in there. Does anyone see that too?
Oregon 18200.
View attachment 972543

The 18200X is just a stock pic of a rim drive system, fyi. It's not actually showing a picture of the 18200X drum/rim.

 

[Patrick1903]

If anyone is following, here is the latest I think I've determined about the clutch situation and not getting the drum to spin freely from the clutch. My post is #20, reviving an old thread on the same subject.
041 Clutch Issues Thread
https://www.arboristsite.com/threads/stihl-041-drum-differences-need-help-please.319158/post-7701841

 

[Patrick1903]

If anyone is following, here is the latest I think I've determined about the clutch situation and not getting the drum to spin freely from the clutch. My post is #20, reviving an old thread on the same subject.
041 Clutch Issues Thread
https://www.arboristsite.com/threads/stihl-041-drum-differences-need-help-please.319158/post-7701841

OK - my clutch situation is resolved. Finally able to keep the clutch separate from the drum. THe oil pump washer has a flange on it that points out towards the drum. That flange inserts into the drum inside diameter, which causes the needle bearing to extend out past the shoulder of the crank shaft. So when the clutch was tightened onto the crank, it was tightening down against the needle bearing and locked all of the clutch/drum together. Not good. So filing the flange down to allow the needle bearing to ride inside the crank shoulder solved the problem. Details/pics/video here. What made it tricky is that the part numbers don't mean a whole lot - there is apparently another washer with another part number that would solve the problem (no flange). But the parts are hard to find.
https://www.arboristsite.com/thread...s-need-help-please.319158/page-2#post-7709909

 

[Patrick1903]

So now I'm back to my original problem. I was able to run the saw a little bit today. Starts and runs great. But then seems to die hard/fast. I was also seeing a fair amount of smoke, and I noticed on my brand new bar and chain - it's getting a lot of oil - but the oil appears to be dirty. Could this dirty bar oil be due to the apparently common issue of the o rings in the oil pump leaking into the crankcase? Could the oil expelled by the pump somehow be picking up mix from the crankcase? The saw ran well for 5 mins or less, but I wasn't putting it into wood. Revving some and idling. Please see picture.


Though this was also happening with the original carb last year when all of this started (after the top end was replaced and the saw had sat for years prior to the top end replacement) - I am going to put the original carb back on (G&D kit and cleaned last year) - just to minimize the non OEM variables.

 

[Patrick1903]

OK, I put the old Tillitson carb back on. Saw ran pretty well with it on, as far as starting and basic tuning ability. I could run the low side in all the way on the chinese carb, and it wouldn't seem to affect anything. The Tillotson defintely responded when I adjusted the high/low - not that I am trying to perfectly tune right now, since I think I have an oil issue. Ran the saw for 5 more minutes with the Tilly back on. Adjusted slightly for idle, low, and opened high slightly and was able to hear it 4 stroking. Again, not trying to get it perfect yet, and didn't put in wood. So the really noticeable thing is that it is really puking oil. Dripping on to my boot, slinging onto my pants, all over the bar. THe oiler adjustment is turned down all the way. Is that normal? I remember back in my early posts one of my issues seemed to be excessive oil that seemed to have carbon in it.

See pics of oily bar and of the plug after running a few mins. Sorry @Vintage Engine Repairs - I couldn't help looking at the plug after running it some and revving a little - was just curious to see what it looked like. Looked ok, but I hadn't pulled it after I shut it off - so it wasn't wet. A little dirty though, i think. I don't have any wood I can cut right now - so cant really test it in the wood (maybe tomorrow??). And also @Vintage Engine Repairs - one of your primary concerns was if the CDI module that used to be in there could have been causing issues after heating up - so I still haven't tested that scenario now with the points/condensor that are back on the saw. Thanks again for the assistance with me getting that straight. The hard die I experienced earlier today (referenced in last post) made me wonder if it was not the ignition. Hard to tell until I cut for 15 mins with it. But the points seems really good and sound nice so far.

 

[Patrick1903]

Cross referencing to an over-oiling thread from 14 years ago. I posted there as well. I took the pump out and will replace the two seals. Hope that helps with the over-oiling problem - though I am not sure why bad seal/ring on the pump would cause it to over-oil. I would think those would normally solve the problem of under-oiling.

https://www.arboristsite.com/threads/1976-stihl-041-farmboss-oil-pump-leaks-bad.52458/post-7710644