1989 ATK 406 Restoration

Micahdogg
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3/28/2020 4:48pm
Pulling the DU bushing and oil seal from this end cap was a little complicated. I was able to snake a bearing puller in from the outside...just past the dust seal, spread it out to grab onto the bushing, then put it all under tension via the c-clamp. After adding heat, it naturally started to pop loose and come out the other side of the end cap. After a few turns of the c-clamp, it popped out. The video shows some more details of the contents, but this is all required to change the dust seal. Also I installed a new DU bushing to tighten up the whole thing since the old bushing was worn. Also a o-ring was hidding in there...its actually the last item in the cap (visible from the outside). It looks like the taper of the dust seal fits inside th o-ring to give it a bit more tension. This thing was a PITA to get onto the shaft...it has a lot of tension now with new stuff.



A vid of some of the process.


Here is the oil seal and o-ring. It fits into the seal head. Im showing the old stuff from the front and then from the back. You can hardly tell a difference, but the oil seal (the piece inside the o-ring) is tapered on one side. I had to get out a caliper to find the small side. The taper needs to point towars the piston as the oil and nitrogen pressure help it to seal.







Got the shaft assembled again. Rebound adjuster is set right where it was before. All I need is to install a new piston band and the shaft is ready for install.



Also, the oil seal doesnt really stay inside the o-ring when its all on the shaft. If you move the seal head around at all, the oil seal pops right out. When you thread the end cap down, it physically presses on the oil seal to hold it in place. I pushed them both together and sure enough it pops right into place. I recall upon disassembly the old oil seal just fell out and was loose on the shaft.
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Micahdogg
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3/28/2020 8:34pm
I got it together and I'm stumped. It would appear that the oil seal does not seal until under pressure. So you cant really adjust fluid. You add fluid, screw the end cap into place (with loctite?), air it up to 200 psi and your seal head pushes up against the end cap and presses that little oil seal in place (inside the oring in the seal head). Presto. With pressure it will seal, but without pressure you never get enough force to lock the seal head and end cap together.

Thats the trick with hoping you bled it and hoping your piston is in the correct place. At least thats what I think.

For now, bleeding is the least of my problem. Im just trying to get the damn thing to seal.
Micahdogg
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3/29/2020 7:52pm
Boy it sure would be nice to have a manual. Or some torque specs. Or some pointers. But all I've got is a 45 minute conversation with a guy who gave me a quick rundown of this shock.

Needless to say, I spent most of the day fussing with this thing, going in circles and practicing my disassembly and reassembly skills (which I'm getting quite good at).

Here is a picture of my $20 harbor freight vacuum pump. I found out if you pull the shrader valve core you can use it to draw the piston and fluid down into the reservoir.


I also spent $5 on a hose barb and rubber stopper. I drilled the stopper, inserted the barb and wedged it into the compression valve bore. Once I got the shock sealed up, I turned it on its side and used the vacuum pump to draw fluid and bubbles out of the shock. The bubbles rise and the fluid falls. Just keep fluid in the line.



Here is a video to capture some of the frustration.


Now for the good news. I figured out that the dust cap needs to be sealed. For some reason I thought it would be fine if i just torqued it down, but no dice. So I wrapped it about 3 times with teflon tape, torqued it down, shot 220 psi of Nitrogen into the thing and presto...it works! The shaft is dry, the shaft rebounds on its own. It acts just like it should now.

But...the dust cap is leaking slightly. It left a few drops over 10 minutes. So I have it sitting over night to see what kind of puddle it leaves. I'm going to have to tear it down one more time and figure out a better sealant for that dust cao and then hopefully I will be done.
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Micahdogg
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3/31/2020 8:07pm Edited Date/Time 3/31/2020 8:08pm
Took it apart again. Talked to Kelvin at Cycle Shed Racing and found out I had a snap ring in the wrong position. Once I moved it, everything was much happier. Shes all charged up again, no leaks, and ready for action. The dust cap gets torqued to 35-45 ft-lbs btw.

Forks will be next. I hope to have them apart this week.

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The Shop

Micahdogg
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4/1/2020 5:11pm
Got the frame, swinger and shock spring back from the powdercoater. It looks so much better than the blue IMO.

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Micahdogg
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4/3/2020 7:52pm
Thinking of cross drilling the rear brake rotor. Basically to just make it look cooler.



Also got the badge reattached to the frame. The blue looks pretty cool from the red frame.

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Bearuno
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4/3/2020 10:48pm Edited Date/Time 4/4/2020 6:36am
Great effort with the Shock!

It's usually something along the lines of your snap ring positioning that you sorted out. Things like that, bite you in the arse.

Years ago, I was the OZ tech for major suspension manufacturer, and, I'd have to reverse engineer each new type of shock, as they were always a bit 'behind', continually, with rebuild specs and instructions. It drove me absolutely nuts.

Even when you got them - specs and instructions - much of the time they were not particularly useful. Informing them of that, upset a few, endeared me to a few. It's the way it goes.

Keep going, it all looks great, and you re showing you are far more than the usual 'bling-er' - you're a do-er.

Are you going to keep the 406? I hope you do / you can.
Micahdogg
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4/4/2020 7:06pm
Yeah Im keeping it. I hope to ride it, but thats what I said about the CR500R too and so far I just boot around the yard on it.
Micahdogg
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4/5/2020 7:25pm
Started cleaning the engine. There are some huge chunks of black powdercoat missing from the cases. I'm not even sure if I'll waste my time touching them up.



Also busted out the "classic" 2002 YZ250F that I did a really detailed build on. It ran like a charm. I actually enjoyed riding it. I had the wife take some footage of me booting around on the pit bike trail in back.




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Micahdogg
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4/9/2020 8:24pm Edited Date/Time 4/9/2020 9:16pm
Got the engine cleaned up. I decided to touch up the black engine paint afterall. New bearings in the swinger, fighting with the axle nut and making a spacer for the countershaft sprocket. I need to get the A-Trak componets and chain back on before doing much more on the axle. I want to make sure my sprocket alignment is good.




Also took another vid:
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Micahdogg
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4/10/2020 11:01am
I hate to spend this much time on something that is purely cosmetic, but I really can't stand this solid disc.

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Micahdogg
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4/10/2020 9:41pm
And 4 hours later on some of the cheapest equipment that Harbor Freight has to offer, I've got a rotor that can be described as "Not as bad as it could have been." In all honestly I think it turned out pretty good and seems to fit the look of the bike better.


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Bearuno
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4/12/2020 4:34am Edited Date/Time 4/12/2020 4:44am
I'd say it's just a Wrong Axle.

No bloody way I'd ride anything with just a few threads of nut engagement. And No manufacturers OEM axle would be like that. It doesn't look like it's simply you having a spacer / whatever under the head of the fixed axle nut (that doesn't look like it's got a lot of protruding thread, that could also perhaps account for the lack of thread, on the RH side), that's making the axle 'short' .

If the wheel is slipping in without you having to spread the Swingarm, well, I'd say it's not wheel spacer related. To get full nut to swingarm engagement, with thinner spacers, you'd be pulling the swingarm in / together by quite few Millimeters.

I think the original axle end 'keyed' over that square in the LH side of swingarm. So only 1 tool was needed for rear wheel removal. The other blokes who've posted here who had ATKs may know the full details - if they had the same sort of swingarm as yours - there were a few different Swingarm / Brake / Chain adjuster set ups, I believe, over the years.
Micahdogg
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4/12/2020 7:03am
I actually found the problem last night. The wheel was a little tight to fit before but now it slips right in.

I also found out that my A-Trak components are all jacked up. It appears there was a chain detrailment that caught up inside the upper. It has a fresh looking Chinese bearing inside. It also has some rigged up stuff that I have yet to determine if it meets my rigging standards.

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Bearuno
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4/12/2020 7:59am Edited Date/Time 4/13/2020 1:25am
You've got to wonder about the IQ , or sense of self preservation of some people. My thought of it being a mis-used axle is topped by the stupidity of not seating bearings / spacers properly.

Not sure of your Idle Sprocket problems, but I think ADB have new ones, with a better bearing etc set up, available. To me they were quite reasonable in price. They are a Major part of your bikes design and function, so you really shouldn't cheap out on them / do a bodge.

I found them when I was trying to get new idler / guide wheels for my AMP Chain Device I used to use on my CRE, and XR/ CR hybrids. I loved some aspects of it's performance, but grew leary of those parts age, so, went back to a standard chain run, in the last year and a bit. It took quite a lot to get used to chain torque reactions, again.
Micahdogg
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4/12/2020 5:38pm
Thats awesome bonseff! They were really dwelling on the ATK at 2:51. Also cool to see some banners around the track.
Micahdogg
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4/13/2020 6:19am
Bearuno wrote:
You've got to wonder about the IQ , or sense of self preservation of some people. My thought of it being a mis-used axle is topped...
You've got to wonder about the IQ , or sense of self preservation of some people. My thought of it being a mis-used axle is topped by the stupidity of not seating bearings / spacers properly.

Not sure of your Idle Sprocket problems, but I think ADB have new ones, with a better bearing etc set up, available. To me they were quite reasonable in price. They are a Major part of your bikes design and function, so you really shouldn't cheap out on them / do a bodge.

I found them when I was trying to get new idler / guide wheels for my AMP Chain Device I used to use on my CRE, and XR/ CR hybrids. I loved some aspects of it's performance, but grew leary of those parts age, so, went back to a standard chain run, in the last year and a bit. It took quite a lot to get used to chain torque reactions, again.
I will probably have to buy some new parts for the upper. The lower was much nicer except the bearing is shot. I peeled the cover off and put fresh grease inside for now. If i use common sense I think I can run these sprockets for a little while though.

Micahdogg
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4/13/2020 8:01pm
Got the triple clamps cleaned up. The lower was missing a steering stop bolt, but other than a good cleaning, everything looked to be in good shape. I'm reusing the bearings and races. The frame rubbers for the gas tank came from a 96-00 RM parts lot. Sure beats the janky radiator hoses someone was using.




Also I have two options for bars...dull or shiny. Both are 7/8 Renthals that friends have donated to my garage over the years. The ones that came on this ATK were bent, cheap steel, so either of these will be an improvement.

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Micahdogg
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4/15/2020 8:05pm
I slapped the pegs on to check the shifter lever. Yeah this isn't going to work. Its too short, its twisted up and the tip was welded so it wont fold anymore.



As I was contemplated options I couldn't help but notice how nice this offset Craftsman wrench fit. I'm strongly considering using the meat of it and donating the splined end and (non) pivoting tip from my current one. Too bad the chrome wont survive.

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Bearuno
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4/15/2020 8:28pm Edited Date/Time 4/15/2020 8:31pm
Please, don't do that.

It ranks right up there with some of the lunacy we see on Craigs List sales. You know, the complete and utter shyte type bikes / mods that Meth / Oxy / Smack heads think are great .

Plenty of gear levers with full, correct splines cark it, either from impacts / being run lose.

Something with minimal, non full contact 'teeth', such as a multi point ring spanner, won't last any sort of usage.

You've got a dual usage, inner and outer set of shafts there you risk damaging, and they might be a bit expensive, or, hard to get.

If the splines on the gear lever are healthy and it clamps to the shaft well, just make a new folding tip (well, just go looking for another decent / high quality folding lever at say, a wreckers) and construct it to the correct length and height setting to suit your Herman Munster feet.

Sorry if I seem impertinent with this, but hell, you're doing a great job, making a classic bike, live again, and fit You . That ringy idea, is well, just as I described it in my 2nd sentence, above. Or was that ring spanner 'thing' a joke?
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Micahdogg
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4/16/2020 6:48am
Lol...I may be Herman Munster in height but my size 13 is somewhat normal. I was only talking about using the thin section of steel in the middle of that wrench.

I like the long skinny profile because it will be friendlier to the engine case during the inevitable scuffs and it wont protrude out as far as the round stocker. That left side is pretty crowded by the peg so any room will help.
Micahdogg
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4/16/2020 7:43pm
Gas tank is done. Ive done some thorough refurbishing on tanks before but for this one I gave it a quick polish job. I just dont have the patience to remove all the little imperfections anymore.

The seat mounts up ok. I was interested in seeing how all 3 colors of red mesh together. The side plates are yet another color, but at least those will have some big, white number plate backgrounds to block it out.

Also got the intake tube cleaned, test fitted the air filter and dragged the carb out from under the toolbox. It will probably be next up (I keep avoiding the forks!).

Bearuno
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4/16/2020 8:59pm
Micahdogg wrote:
Lol...I may be Herman Munster in height but my size 13 is somewhat normal. I was only talking about using the thin section of steel in...
Lol...I may be Herman Munster in height but my size 13 is somewhat normal. I was only talking about using the thin section of steel in the middle of that wrench.

I like the long skinny profile because it will be friendlier to the engine case during the inevitable scuffs and it wont protrude out as far as the round stocker. That left side is pretty crowded by the peg so any room will help.
Oh, I took it as you were going to use the ringy section on the spline. Woohoo

Older Huskies (as in, Swedish Huskies) had neat little folding tips, on a small section, high quality 'arm' that might be of use to you. I used to use them, quite a few years ago, on many projects.

Though, I had mates with various bikes with the 'inner and outer' KS and Gear Shaft set ups, that made up more malleable, flat bar mid sectioned folding levers, combined with Brake Snakes, to protect the double shaft set up.
Micahdogg
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4/16/2020 10:00pm Edited Date/Time 4/16/2020 10:06pm
"Oh, I took it as you were going to use the ringy section on the spline."

For phucks sake...thats the section I wont use. Gesus...its like you dont even know me.

Can you post a pic or link to the Swed Husky shifters you are talking about. I'm curious about that.

PS I was thinking of a brake snake for the same reason!
Bearuno
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4/17/2020 12:55am Edited Date/Time 4/17/2020 12:59am
Hey, over many years, I've seen blokes do great jobs, but suddenly they do strange things......... usually towards the end of a project.

My 'puter's dead, so, no access to my pictures. I'm stuck on my 'phone, or this weird little tablet.

You'll find a bazillion pictures of old Huskies though, here in the 2t section, and, the web in general.

But, they are pretty much like your original ATK one - slim 'arm's, made from high quality material. And, quite possibly expensive, or hard to get. Have you got a MC Wreckers near you., so you can find a donor, folding tipped arm? Though, it looks like you are in a rural area.
Micahdogg
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4/17/2020 9:11am
I can get another ATK shifter and use as a donor (or another shifter from a different bike) but its such a simple part I cant see the point in using a donor. My splines are good and I think I can get the folding tip working again.
Micahdogg
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4/20/2020 3:46pm
I havent torn into the carb yet, but the outside is clean so I mocked up the airbox to see how it was all fitting. The airbox side has a 2.75 inch outlet and the carb has a 2.5 inch inlet.

The prior owner had a conglomeration of zippy ties and a janky rubber boot. While at Autozone the other day I noticed this guy sitting on the shelf for $10. Its 3 inch to 2.5 inches, but it was close enough. I just had to trim the front and rear (and use brake cleaner to removed the tacky logo). Looks like a winner.


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