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Complete Stihl 041AV Super step-by-step rebuild - very pic heavy! (for 041 newbies)

Discussion in 'Chainsaw' started by Brmorgan, Feb 16, 2010.

  1. Brmorgan

    Brmorgan Addicted to ArboristSite

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    Today I finally got around to tearing my 041AVS down and rebuilding it onto a "better" case. Still not perfect but the best AV case I've seen so far.

    Here's what I started out with:

    [​IMG]

    Here I already have the cylinder mounting studs inserted into the case with blue threadlocker for added security. Regular 61cc 041 cylinders use regular mounting bolts which only go through the base flange instead of the entire cylinder.

    You can see this case's only two defects - the broken bolt eye at the very top of the photo that I repaired, and a crack in the thin metal on the bottom of the case below the flywheel area, at the very lower right in the photo. I haven't tackled this one yet because I'm not quite sure how to do it right. Not sure if some mesh and a thin layer of JB on the backside would help it or if it's worth the effort. This is a major weak spot with this case design. I also installed a brand new plug wire in this unit, which must pass through the rubber grommet to the right of the bottom-right cylinder stud. The kill wire passes through a smaller grommet in the top of the case, visible at the very bottom edge of the photo.

    [​IMG]

    Got the points ignition installed and hooked up to the new plugwire. I tried an electronic setup that I had but couldn't get it to produce a hot enough spark to start the saw, so back to good ol' reliable points it is. The points are located under the black housing at 6:00 in the photo, and the round grey cover tab can be pulled out to inspect and service the points themselves. There are three wires going to the condenser - the bottom one is the timing wire from the points, the top one is the kill wire going out through the case, and the one on the left is the incoming high-voltage wire from the coil.

    [​IMG]

    This is what the SEM electronic ignition coil looks like. The high-tension coil is missing in this photo but looks similar to the points coil, just without the metal "ears" sticking out the ends.

    [​IMG]

    These are the different flywheels - the one on the left is for the SEM electronic ignition, and the one on the right is for a points ignition. You can barely see the timing lobe on the inner shaft of the flywheel - it goes from about 9:00 to 12:00 on the shaft. Notice the windows in the flywheel for checking the point gap as well.
     
    Last edited: Feb 16, 2010
  2. Brmorgan

    Brmorgan Addicted to ArboristSite

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    61cc --> 72cc cylinder differences

    Since this has come up a few times I thought I'd put up a few pictures just to show both side by side:

    [​IMG]

    The Super 72cc cylinder is on the left, and took a hit at the scrapyard before I rescued it which busted three fins off the top at the left. I've ported the exhaust out a bit but it was originally about the same size as that of the 61cc cylinder. The lack of recesses between the port and the bolt holes is one giveaway for a Super cylinder.

    [​IMG]

    Super cyl. still on the left. Not too much difference here; the fin design is a little different but still very similar. One big difference you can see though is the line of holes through the fins to allow access for cylinder bolts on the 61cc cyl. whereas the mounting stud "tubes" are molded solid right into the cylinder on the Super.

    [​IMG]

    The bases are also a little different. The Super cylinder, still on the left, doesn't have the larger cutouts around the case-to-cylinder transfer areas. The bore is 4mm larger though so I'm not sure if there would be any advantage to grinding anything like that out. The small notches on the Super cylinder did, however, have very sharp edges where they transitioned into the cylinder at the top, which I smoothed out a bit with the Dremel when I did the port work.

    [​IMG]

    [​IMG]

    Pretty obvious here, Super piston is on the left. Not really any significant differences other than size though. I had the one ring out of the Super piston to make it easier to get the cylinder on and off to do squish testing etc.
     
  3. Brmorgan

    Brmorgan Addicted to ArboristSite

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    [​IMG]

    Here I have the piston re-mounted with some .032" fine solder taped to the top to test the squish. At first it didn't even touch it, so I took a bit off the cylinder base with some 80 grit sandpaper on a piece of flat steel I keep on my bench for such things:

    [​IMG]

    Took a while but it got it down to .024" without too much effort. Light, easy strokes are the name of the game or the cylinder wants to dig in and tip, creating an uneven surface.

    [​IMG]

    I don't have ring clamps and these Super cylinders are a bit tricky to get on with all the studs in the way, but I got it done with a bit of lube. I secured the cylinder with four brand-new Nylon lock nuts. The other two holes in the cylinder are for mounting the rear/lower handle section. I should note I left the base gasket out and used some Permatex MotoSeal to seal the base.

    [​IMG]

    Polished the flywheel in the wire wheel, lined it up with the keyway, and cinched it down with my 18V cordless impact driver.

    [​IMG]

    Got the fan mounted now with the three screws around the center cup section. All my 041s use Fairbanks-Morse starters, but some have pawl-type which need a fan with a sawtooth-type pattern in the center to engage the starter pawls.
     
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  4. nanuk

    nanuk AboristSite Guru

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    Looks good.

    Keep in coming!

    :popcorn:
     
  5. Brmorgan

    Brmorgan Addicted to ArboristSite

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    I repaired the bolt ear the same way I did this one on my other 041 a month ago:

    [​IMG]

    Here's the one I repaired today:

    [​IMG]

    Only difference is that I cut the notch wider to accommodate two washers instead of one for a bit of added strength (hopefully). The first one I did is still holding up okay. I apply a bit of JB Weld to the washers & groove before I mate the two, then I apply quite a bit of JB to cover up the whole works, using a couple pieces of packaging cardboard etc. as "forms" to keep it in shape. Once it's cured I file/grind it to shape, and locate and drill the hole. This one thankfully doesn't need to be tapped since the bolt only goes through it to the mount hole in the rear handle section:

    [​IMG]

    On goes the rear section of the saw. At first it's only secured by the two bolts into the top end of the cylinder in the center of the photo. I like to leave these bolts slightly loosened during assembly to allow a bit of play to help everything line up, rather than risk crossthreading a bolt or something.

    [​IMG]

    It's nearly impossible to port match these mufflers very well due to the flange/pipe design, unless a guy was to add some material behind the flange with a welder. I've thought of doing it but haven't tried yet. I ground the flange out to at least smooth out the lines a little bit; it's still a pretty abrupt transition but better than having 90° edges around the perimeter. As it is you can see the copper brazing that mates the flange to the pipe.

    [​IMG]

    Got the muffler mounted with the two flange bolts. The two bolts below the muffler box have to wait for a few steps. This is the more modern "firesafe" muffler which can accommodate a spark arrestor screen. It won't be, though.

    [​IMG]

    Here the intake block and heat shield are secured. The gasket looked a little suspect so I decided a layer of MotoSeal was in order rather than cutting a new one. Not sure how it'll hold up; we'll see.
     
    Last edited: Feb 16, 2010
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  6. SkippyKtm

    SkippyKtm The Lorax, my FIL rip...

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    These Kind of Threads are what makes Arboristsite Great! Great job Brad, Keep 'em Coming, and Thank You! This is definitely getting Bookmarked for reference!:clap::clap::clap::cheers:
     
  7. Brmorgan

    Brmorgan Addicted to ArboristSite

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    Mounted the top section now:

    [​IMG]

    There's one carriage-style bolt that goes through the rear AV mount, and two 5mm assembly bolts that mount it to the front AV.

    [​IMG]

    Now that the top handle's on I can mount the carb baseplate, install the throttle linkage, and mount the carb. The impulse line also needs to be hooked up to the hose nipple on the case next to the orange oiler adjuster, and to the nipple on the backplate of the carb, NOT the one on the side. That one is for the fuel line.

    [​IMG]

    The little grommet on the kill wire goes into a recess in the side of the heat shield. This is one easy way to remember how to orient the heat shield if you ever forget.

    [​IMG]

    Got the new plug boot put on the wire. The second grommet on the plug wire goes in a recess in the side of the rear handle section and is held in place by the tank/recoil housing:

    [​IMG]

    Secure all the bolts but the top-right one for the time being. The next step will show why.
     
  8. leeha

    leeha Addicted to ArboristSite

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    Great thread, Nice to see another
    old saw come together.
    Keep up the fine work.


    Lee
     
  9. Brmorgan

    Brmorgan Addicted to ArboristSite

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    [​IMG]

    I choose to mount the filter plate after the tank housing, because that way I still have easy access to the fuel lines etc. around the carb to make sure there's a good tight fit between the tank and carb. First attach the choke linkage (black tab at top in photo), and then fit it into place and secure it with two 8mm X 5mm nuts onto the carb mounting bolts. It is also secured to the rear handle and tank sections (lower right in photo) via a thin "bar" piece that fits between the two main parts, and has an elongated hole at the lower end to allow for some movement.

    [​IMG]

    Got the freshly re-rubbered full-wrap handle back on it. I'd never seen one of these on an 041 before but my old friend had one kicking around his '41 parts box so I made an offer on it. I think it looks pretty mean on the Super at any rate.

    [​IMG]

    Now on to the oiler and clutch. The oiler is linked to the clutch drum via a washer with a hole and a pin. The pin fits into a hole in the oiler and a hole in the sprocket, or in my case, a notch in the rim splines.

    [​IMG]

    Next I installed the sacrificial plastic wear strip along the back side of the PTO area - it has one small tab that fits into a recess in the case at the bottom, and one screw that secures it at the top, visible above the clutch in the photo. The correct order for the clutch assembly is oiler washer - drum bearing - drum - ~2mm spacer bushing - clutch washer - clutch. Some clutches are held on by separate nuts; this one has it built into the center plate. If you have an 041 with a sticky clutch check for the spacer bushing that must go between the clutch and the shoulder on the crank; otherwise the clutch will suck right down against the drum when you tighten it down.

    [​IMG]

    Now the muffler guard can go on. This piece has three bolts along the bottom edge and one at the top-left of the muffler. This is why I like to leave the bolts loose that hold the rear section to the cylinder head - sometimes these holes don't all like to line up at first with the muffler, which is firmly affixed to the cylinder and can't budge. Once the two lower muffler mount bolts are tightened down though you can suck it down tight to the cylinder. That repaired bolt ear at lower right seems to be working like a champ so far; now to see how it holds up to runtime.
     
  10. Brmorgan

    Brmorgan Addicted to ArboristSite

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    After a quick shot of fuel down the throat and a couple pulls, she fired right up. Not too much though - I don't feel like eating clutch pieces with it free-revving. Now that I know it's pulling fuel on its own properly I put the air filter and cover on:

    [​IMG]

    [​IMG]

    I guess the "Electronic" model plate is a misnomer now... Oh well, I want to find a Super tag for it anyway.

    [​IMG]

    I mounted the 24" hardnose bar and 3/8" skip chain that was on the 041 G, and put the 28" 3/8" setup that was on the pawnshop 066 I just got on the 041G instead, since that's about what I figure it would be happiest with anyway. I even managed to find a "Western" (if you will) clutch cover for this one to go along with the full-wrap bar - it has the felling guide line, though I forgot to make sure it showed up in the photo here. I've never seen another one with that line yet.

    So, here's what she looks like all wiped down after assembly:

    [​IMG]

    I plan on changing out the oiler cap to the same style as the fuel cap - I hate hate hate those square oiler caps! No rational reason why though. :) I also plan on getting a second spike on the inside as well; they're pretty easy to come across and it looks a lot better IMO.

    All in all it could use a bit of paint around the corners but it's a real nice solid work saw now, and runs like a charm, as all 041s do. Now to find a tree to bury the bar in!
     
  11. belgian

    belgian Addicted to ArboristSite

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    Nice job, Brad !!

    I've done a few of these and recognize everything you have shown ...:clap:

    The oiler is a bit peculiar on this one, just make sure the O-rings are still in good shape.
     
  12. southbound

    southbound AboristSite Guru

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    Great how to!!!!!!!!!!!!!!!!!!!!!!!!!!!:clap::clap:
     
  13. matt9923

    matt9923 Stihl bustin knuckles

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    nice job, that saw looks great!
     
  14. caotropheus

    caotropheus ArboristSite Operative

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    :jawdrop::jawdrop::jawdrop::jawdrop::jawdrop: Fantastic! Brad, your step by step explanations and pictures are breathtaking. Thanks a lot.
     
  15. Brmorgan

    Brmorgan Addicted to ArboristSite

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    I never had to touch the oiler on this one, so I didn't get any pictures of that. I did just have to replace the one on the 041G I got going last week. I have a couple spare cases left though, so maybe I'll pull one today and take some pics just for completeness' sake.
     
  16. Brmorgan

    Brmorgan Addicted to ArboristSite

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    That may be, but it sounds better! Thanks!
     
  17. SpaayDawg

    SpaayDawg ArboristSite Operative

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    Great to see other 041 enthusiasts, great build, and attention to detail. Gotta love that exhaust tone!!:rock:
     
  18. djmercer1

    djmercer1 ArboristSite Operative

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    i think they(041/051/075) were bought with the fuel/oil cap combination.... mine was anyway...
     
  19. jkilov

    jkilov ArboristSite Lurker

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    Hi, I'm new to the forum but not new to 041s.

    Mine is an early model, one of the first AVs to hit the market. Couple of things I'd like to add:

    - The clutch spacer you're talking about was not part of my saw. It came added with the "new"-style clutch drum kit which had a wider sprocket than the original, hence something was needed to space the clutch further out.
    - Some had no muffler guards, just an extended bar cover that wrapped around the muffler
    - Plug hole has only a few threads which can easly strip
    - Rear handle mount is a weak point, specially when operators step on it like elefants
    - Chain tensioner mechanism likes to develop slack over time
    - A few parts of the scissor starting mechnism like to act up
    - Air filters get dirty real quick, or is it just me?

    Bottom line, it's a great saw with a few detail flaws. A bit too heavy and slow for modern standards but i actually still use it.
     
  20. Brmorgan

    Brmorgan Addicted to ArboristSite

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    Hm, well this is about the fifth or sixth 041 I've worked on and all of them so far had that spacer bushing against the shoulder of the crank. This Super is using a rim-drive drum that I bought after the fact and the bushing was not part of that kit, it was already on the crank; the rest were all spur drives and they all needed the bushing too. My 045AV is the same way. So I dunno. I do agree though that there have been many minor variations on these saws over their 40-odd year lifespan so I doubt I've seen all of them

    I think the other muffler/side cover style you're thinking of is the non-AV one like this one of mine:

    [​IMG]

    They won't fit the AV models because of the two extra mounting tabs on the bottom of the AV mufflers though.

    Do you mean the rear handle is weak where it mounts to the cylinder, or at the rear pivot point where both sections are mated through the rubber AV bushings? If the latter, the biggest thing to keep in mind is to not over-torque the carriage bolt that goes through those pieces. Since the rear section fits around the AV bushings like a "Y", if you put too much torque to it it will just compress the rubber bushings and crack the "Y" since Magnesium isn't exactly very flexible.

    The main problem I've seen with the tensioners is the bolt getting bent by people trying to over-torque it either with the bar nuts still tight or with the bar already at the end of its adjustment channel so it can't move any further. That, and worn, rounded-off nubs that just slip rather than engage the tensioner hole in the bar.

    The Fairbanks-Morse starters on these are pretty sensitive to dirt and oil. If the friction washers get oily or shined up they won't engage the shoes properly and it'll slip. It's an easy fix once you're accustomed to putting them together. I have to build a starter for the 61cc 041AV I'm working on this afternoon (last one of four, finally!), so will take a couple pictures of that as well along with the oiler.
     

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