Stihl 041 AV FB Rebuild / Restoration

[ReliableRust]

I do have a cover washer installed but I'm not certain it is the correct thickness. The cover washer that's installed is not original to this saw, the original one had a loose pin. I'll compare them tonight to see if there is any difference in thickness.

 

[Bob Hedgecutter]

I do have a cover washer installed but I'm not certain it is the correct thickness. The cover washer that's installed is not original to this saw, the original one had a loose pin. I'll compare them tonight to see if there is any difference in thickness.

I'm no expert, but pretty sure there are two thicknesses of said cover washer and you need the one with the pin fitted for an 041- if the pin is missing it is the shank end of a 2.5mm drill bit either 10 or 11 mm long.

 

[ReliableRust]

The threaded section is definitely longer on my new crank vs the original, so I think that was the cause of the problem. However, it is possible that the wrong thickness of cover washer is contributing as well. You are correct there are two options in the IPL. I'm using the stack up, highlighted in red. I think if I had the spacer I've highlighted in yellow, then it would put a gap between the clutch drum and clutch, allowing proper clutch function. Did a little searching for that p/n but didn't come up with any sources for one.

 

[ReliableRust]

I'm no expert, but pretty sure there are two thicknesses of said cover washer and you need the one with the pin fitted for an 041- if the pin is missing it is the shank end of a 2.5mm drill bit either 10 or 11 mm long.

You were right about the two cover washers being different sizes. The replacement is on the left and original on the right.

I tried both but they don't seem to affect the location of the sprocket or clutch drum. The raised lip on the original slips inside the sprocket, thereby just moving the bearing further out.

Here's with the original installed. The bearing sticks out past the lip on the shaft.


With the replacement, the lip on the shaft protrudes from the bearing.

I think my best path forward is to use the replacement then fit a spacer in there to extend the lip on the shaft out beyond the clutch drum. I went by the hydraulic shop in town and they hooked me up with a short length of scrap 1/2 x .049 steel tube.

It fits over the threads and seats nicely on the lip and the sprocket/clutch drum slips over nicely. Now it's just a matter of figuring out the proper length. Fist attempt was too short, once I blipped the throttle a few times the clutch tightened up and started dragging on the back of the drum again.

 

[ReliableRust]

My 2nd attempt at the spacer seems a bit long, this causes what I think is excess axial play in the clutch drum. I'm getting about 1.15mm of movement outta the drum, I'm concerned the could cause wear on the oil pump drive pin. I'm going to test it out and maybe sand down the spacer some more.


These photos show how I'm measuring the axial play in the clutch drum...

 

[ReliableRust]

What do you think should I paint the sight lines and raised letter for "Mix" and "Oil".

 

[Bob Hedgecutter]

Yep- will help detract from the glare of the white.

 

[Woodslasher]

Yep- will help detract from the glare of the white.

Must....not....derail....thread!

 

[Woodslasher]

Yep- will help detract from the glare of the white.

I do agree with Bob, though. I've been known to get bored and use a paint pen or Sharpie to draw in the sights on my saws 'cause they'll look cooler for the week that the black ink/paint stays on.

 

[Bob Hedgecutter]

I do agree with Bob, though. I've been known to get bored and use a paint pen or Sharpie to draw in the sights on my saws 'cause they'll look cooler for the week that the black ink/paint stays on.

Try using the sharpie type marker designed for marking cattle ear tags- that ink sticks a whole lot better after the as per instructions 3 coats.

 

[ReliableRust]

Ah good tip! I did the first one there with rustoleum and a very fine detail paint brush. It was not easy! Deep breaths... steady... steady... Oh crap I messed up! Quick wipe it off with alcohol and paper towel!

 

[Vintage Engine Repairs]

Well I hit a bit of a snag on the clutch. During disassembly I damaged the threads on the crankshaft while trying to remove the flywheel, so I got a new crank from a local guy who sells parts. I had noticed the threads were longer on the clutch side of the crank but didn't realize it would be an issue until I got it all together. I guess some sort of spacer is required as the clutch is bottoming out on the chain sprocket (cup) instead of hitting the collar on the crank. I tried 3d printing a plastic spacer, but I feel like some metal is going to be required for a long term solution. Someone said they used a piece of 1/2" stainless tubing as a spacer, so I might try hitting up the local hydraulic supply house to see if they have a piece of tubing that will work.

Please let me know if you've got any other ideas. I was think possibly grinding down the back of the sproket so it slides down the crank further, allowing the shoulder on the crank to protrude.
View attachment 903556View attachment 903554View attachment 903557

Yes, I don’t recommend hitting cranks even with a brass hammer or rod. I own about 8 pullers to avoid it.
Take that crank back out and fix the original one. I have had excellent results with small assorted files. A dremel and fine cutter wheel too, but use it as a last result.
I have never had good results with a thread file on such hard steel like cranks.

Take some close up pics of the damage.

Don’t get creative cutting this that and the other to make the other crank work.

 

[ReliableRust]

Yeah I know putting the correct crank in there would be the most appropriate fix. I had the nut partially screwed on and was hitting it with a brass hammer. The threads gave way in the nut and rolled over the threads on the crank. It's all put back together though and my spacer is working for the time being, so I'm not real excited to tare it all back apart again.

 

[ReliableRust]

I had it running for a bit yesterday but the idle started to climb then when I hit the throttle it was bogging down. Thinking something must be wrong, I shut it down and inspected the carb. Discovered it was leaking fuel out the front cover weep hole. I've got the carb rebuild kit but was hesitant to mess with it if I didn't have to, now it appears there is no avoiding it. I'm wonder if I should put all the carb parts in or just the "soft parts" or diaphragm/gasket looking bits.

 

[Bob Hedgecutter]

Well, you have spit polished the rest of her- why skimp on the carb?
They are not that difficult to take apart to clean- not much more than the two covers you have to remove to replace the "soft" bits.
You can see from your third photo above the gaskets and such look pretty dry and crumbly.

 

[ReliableRust]

I was just a bit hesitant because I'd read someone saying these were difficult to get right and people often mess it up. I've never rebuilt a carb before, but then again this I my first time wrenching on any 2-stroke, so what the heck why not. I just watched a couple YouTube videos so now I'm an expert, right? Even picked up some fancy terms to throw around... I believe my metering diaphragm to be leaking. I saw I guy drill a hole in a Welch plug to pop it out with a pick, is that the best way?

 

[Bob Hedgecutter]

I was just a bit hesitant because I'd read someone saying these were difficult to get right and people often mess it up. I've never rebuilt a carb before, but then again this I my first time wrenching on any 2-stroke, so what the heck why not. I just watched a couple YouTube videos so now I'm an expert, right? Even picked up some fancy terms to throw around... I believe my metering diaphragm to be leaking. I saw I guy drill a hole in a Welch plug to pop it out with a pick, is that the best way?

Or small hole, insert wood screw, pull the screw- the thing to be EXTREMELY careful about is pushing too hard on the drill to get it through the plug and boggering up the drillings underneath the welch plug.
Nobody makes youtube videos of that sort of goof up- but it can happen.

 

[ReliableRust]

I got the carb rebuilt yesterday. I didn't end up removing the Welch plug, but I swapped everything else. Did a pressure test and it seemed to be leaking a little bit of pressure. It wasn't leaking from from the needle or the Welch plug I poured gas on there and didn't see any bubbles. Wasn't sure what else to check, so I just put it back together. It runs pretty well on the default carb settings. I'm thinking of buying at tach to get it dialed further as I don't have an ear for tuning these things just yet.

 

[farmguywithasaw]

I’m curious what are you using for an oven on your powder coat. Also curious where you get your powder from

 

[ReliableRust]

I’m curious what are you using for an oven on your powder coat. Also curious where you get your powder from

I'm just using an old household kitchen stove/oven, that I got for free off of craigslist. I get all my powder from Prismatic Powders, they're a division of NIC Industries, who also own Cerakote. They have the largest color selection in the world. I used their colors RAL 2004 and RAL 9010 for this saw.