1980 Kawasaki KDX80 back to life

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#1
Hello all, first post but not first vintage salvage,

The latest is a 1980 KDX80, fairly rare as by Japanese standards a low-seller. A rolling chassis with everything else in a box, a giant puzzle. Powder coated the frame, new fenders, re spoke the rear wheel, and redo the seat with a "KX" imprint cover as a "KDX" imprint is non-existent. All new cables. New tank decals. Rebuild the forks, new rear shocks but I might reuse the OEM ones just for that original look, not sure yet.

Engine had a bad lower rod bearing which is the worst of all news as a rod kit is non-existent also - I mean nowhere, not USA, not Europe, not any vintage Kaw supply so the crank shop needs to refit a more modern rod along with the necessary machining and $$. Vapor honed (liquid sand blasting) the cases, jug, head, and hubs.

So... a few photos, more as I finish this up:
KDX80_1_s.jpg
box_of_parts_s.jpg
progress_2_s.jpg
In_process_s.jpg
 

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RM_guy

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#2
I love seeing these vintage bike rebuilds. Mostly for nostalgia but also because I just don't have the patience to do all of that detailed work. Nice job! Thanks for posting,
 
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#3
Some more pics,
Tank before and after, showing the "starboard" side and then the engine cases, just waiting on the crankshaft assembly. Tank is not perfect but considering what it looked like I am happy with the finished product. "It's only new once"
tank_before_s.jpg

tank_after.JPG

motor_2_s.jpg

engine_cases_s.jpg
 

RM_guy

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#4
Nice! Those parts look like they were already in pretty good shape for a 1980!
 
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#5
Getting ready to start the re-assembly, here is the right foot peg and some notes:

I added the black Delrin bushing as the hole for the brake rod was oval shaped.
I machined a SS sleeve for the pivot bolt as the OEM was missing and I couldn't find one.
The brake lever is supposed to be black but I painted it silver - I just like the look and the contrast
It really give me an appreciation for the engineering that went into something so seemingly simple, all the more as this was designed some 42 years ago.
footpeg_assy_1_s.jpg

footpeg_assy_2_s.jpg
 
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RM_guy

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#6
... - I just like the look and the contrast
It really give me an appreciation for the engineering that went into something so seemingly simple, all the more as this was designed some 42 years ago.
=)=)
 

RM_guy

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#8
Looks nice! Ya know...if you don't have a few parts left over you did it wrong =B=)_BGRIN_
 
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#9
Looks nice! Ya know...if you don't have a few parts left over you did it wrong =B=)_BGRIN_
Yep, I hear ya, but with anything like this you have to be careful of what's missing. Over the years these things were taken apart and put back together - either by a 13 year old kid (don't bash me, I was 13 once and screwed things up good =)) or by the dad who thought he knew what he was doing and you get the "I don't think this part is necessary" syndrome. So you need to pay attention, using a good parts guide, to get these things the way they should be. One of the biggest blunders is stuffing a SAE thread bolt into a metric thread - no, they are not interchangeable !

Anyway, a few more pics, the swing arm and the brake hubs:
swing_arm_1_s.jpg

swing_arm_2_s.jpg

hubs_s.jpg
 
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#10
Motor ready to go back into the chassis - first photo - timing. Yes, those are "points", our younger generation may have never seen such a thing but those provide the ignition switch to fire the plug from the earliest motor made to the mid 80's. After working on such, you realize what a wonderful thing CDI is, much like fuel injection.
motor_timing_s.jpg


So... here it is in all its 10hp glory! (the service manual claims 15 hp @ 11,000 rpm but I don't know if I buy that)
motor_4_s.jpg

motor_2_s.jpg

motor_1_s.jpg


Notice the exhaust port on the cylinder below, there is no mounting studs or tapped threads for the pipe, the pipe seals with an Oring and is held in place by the way the pipe is mounted to the frame - first time I've seen anything like this !
motor_3_s.jpg

Next up, final assembly
 

RM_guy

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#11
That is one nice clean motor! I hear ya on points. I used to carry a modified nail file with me on rides just to clean off the points when I was miles from nowhere!
 

RM_guy

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#13
Damn, looks better that when it came out of the factory over 40 years ago!!
 
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#14
Go to put the shifter on (never had the OEM one), this is an aftermarket EMGO, so of course it hits the sprocket cover on the upshift, so I mill out a clearance slot - not sure if it will stay permanent but for now I can try it out.
shifter_1_s.jpg

shifter_2_s.jpg
 

RM_guy

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#15
Isn’t that always the way. Make sure you add some large radii at the bottom of the notch to eliminate any stress risers. I normally remove the sprocket cover. It just collects crap.