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You are here: MacNN Forums > Community > MacNN Lounge > Laminar's Build Threads 001: 1974 Kawasaki H1

Laminar's Build Threads 001: 1974 Kawasaki H1
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Feb 25, 2014, 07:39 PM
 
You guys asked for it, so here goes.

I got this bike from the father of a friend of mine. He bought it in 1975 and rode it all over the US and into Canada until the mid-80s when he started having kids. At that point he parked it in their barn and there it sat until they moved to Texas. He knew I like motorcycles and offered it to me free of charge if I could get it out of their hair. Free bike? DONE.

But I keep forgetting the saying, "There's no more expensive bike than a free bike."

June 2009. Here's what I had to work with:









For those unaware, this bike is a legend. Nicknamed "The Widowmaker," its 2-stroke engine had an extremely peaky powerband that could easily catch careless riders off guard. Add to that a spindly, flexy frame, terrible brakes, and the awful tires available in the '60s and '70s and you have a crash just waiting to happen. And happen they did.

Of course, that peaky powerband was a draw for many, as the bike could run a sub-13 second quarter mile and retailed for $999.
( Last edited by Laminar; Feb 26, 2014 at 06:06 PM. )
     
Laminar  (op)
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Feb 25, 2014, 07:53 PM
 
My initial plan was to get it running and flip it for a quick buck. But after browsing some Kawasaki forums and asking around, that wasn't going to be a good idea. Between each of the three cylinders, the crankshaft has a rubber seal preventing gasses from moving between the cylinders. After 35 years, those seals begin to break down. If the seal fails while the engine is running, the crank, engine cases, and cylinders would all be destroyed.

No problem, I'll just pop some new seals on there and fix it up, right? HAHAHA no. Kawasaki's 2-stroke crankshafts were press-fit together. Disassembly and reassembly requires specialized tools that only a few people in the world have 1. possession of and 2. the skill to use. So it was going to cost me. At that point, I decided if I was going to do the engine up right, I'd have to do the rest of the bike as well.

With a new goal and a more realistic budget in mind, I proceeded with the teardown.

September 2010 (in the time between acquiring the bike and starting the rebuild, I bought, rebuilt, and sold 3 other bikes, got married, and moved).

Tank removed:


Pipes removed:


Like everything on this bike (as I came to find out), original exhaust pipes are rare and expensive, so anything that could be salvaged would be.

When I expressed doubt in my ability to rebuild a 2-stroke engine from scratch, other H1 owners assured me that it was easy - there were fewer parts in this entire engine than in just the cylinder head of one of my Hondas. It really is that simple. Cylinder heads removed:


After removing the cylinder blocks, what was left behind was a dirty, nasty mess of road grime and 20-some-odd years of barn dust:


The far-left piston appeared to have some scoring along its skirts:


If you look closely in the bottom left of that picture, you'll notice that instead of a proper gasket, there's a bunch of black goop used to seal the engine case to cylinder block mating surface. That's a big no-no.

Getting down to bare bones:




Up on the lift:




And down to the bare frame:


More to come.
( Last edited by Laminar; Feb 26, 2014 at 06:08 PM. )
     
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Feb 26, 2014, 10:40 AM
 
It's like archeology. Very cool project. My Dad had one of those "old bikes stashed in the barn" and also successfully gave it away. Need some dates here to appreciate the progress and time involved!
     
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Feb 27, 2014, 09:17 AM
 
Great start. That thing looks in pretty rough shape, but a lot of it is dust and general wear and tear - in my area of the world rust is the certain killer for any vintage outdoor equipment. At least you don't have to deal with that.

My uncle is/was really into vintage bikes that he restored and won a number of bike shows with (I haven't seen him in years but I remember a '63 BMW and his nicest one was a mid-50s ride that was gorgeous, can't remember the name now though).

I live downtown and don't have a garage, but if/when I get one I'm definitely looking forward to my first project.
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Laminar  (op)
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Feb 27, 2014, 12:07 PM
 
Originally Posted by ShortcutToMoncton View Post
Great start. That thing looks in pretty rough shape, but a lot of it is dust and general wear and tear - in my area of the world rust is the certain killer for any vintage outdoor equipment. At least you don't have to deal with that.
The worst of the rust was on the seat pan and the side covers:





The side covers cleaned right up with some sandpaper, but the seat pan took a bit more work as we'll see.
     
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Feb 27, 2014, 12:16 PM
 
Nice work going on, it'll be a great looking bike when completed!
     
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Feb 27, 2014, 06:23 PM
 
September 14, 2010, Let's take a look at the engine teardown.

Here's the engine pulled from the frame, the cylinder heads, cylinders, and side covers are removed. Time to split it!


Yuck, the engine case should definitely not be brown:


Overall, it was actually fairly clean. There was a good bit of rust and pitting on the crankshaft/rods, but the transmission was squeaky clean.



The kick starter shaft:


The shift drum linkage:


The crank:


The shift forks:


September 20, 2010
After spending a long time cleaning up the cases, they looked much better:


September 22, 2010
To make it even better, I applied heat resistant silver paint:


First coat applied:




Properly curing the paint involved three different heat cycles in the oven at 450 degF, 500 degF, and 550degF for 30 minutes each with a 30 minute cool-down period in between. Wife was NOT happy to come home to motorcycle parts in the oven and the smoke alarm periodically going off. I still need to pick up an old oven for use in the garage...

But the results were worth it:


     
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Mar 1, 2014, 06:19 PM
 
How about we do some more cleanup?

September 21, 2010.

Remember the dirty frame?


Everything loaded up in the trunk to go to the carwash:


Once back home and dried off, and loose rust was removed and everything black got hit with Rustoleum's Rust Reformer:




September 22, 2010
After that, everything got several coats of a semi-gloss black to match the original paint.


This angle helps show the final finish - not a shiny, glossy surface, but not completely matte either:


All of the old electronics stayed in place, they just needed some cleanup and a little paint:




September 28, 2010
Once everything was cleaned up, I started putting what I could back into the frame:






     
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Mar 1, 2014, 06:20 PM
 
I cleaned up the original parts as much as I could:




Since doing this bike, I've some decent polishing equipment that would have really made this thing look pretty.

Some parts were beyond help, in which case I had to shell out $$$ for OEM-spec replacments:






I also cataloged all of the bolts, nuts, and screws as I removed them from the bike and ordered all new stainless-steel hardware:


Next up...let's get that engine put back together!
     
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Mar 1, 2014, 09:35 PM
 
Originally Posted by Laminar View Post


Since doing this bike, I've some decent polishing equipment that would have really made this thing look pretty.
A pity you couldn't get all the grime out of the indents. Did you try a pressure washer? It might have sprayed the last gunk out without damaging the aluminum.
     
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Mar 1, 2014, 09:46 PM
 
It didn't get thrown in with the stuff going to the car wash - the rest of the cleaning was done with SImple Green and some wire brushes. Those indents are 100% covered up, though, so it was mostly for my own piece of mind that I cleaned them at all.
     
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Mar 2, 2014, 12:45 PM
 
Originally Posted by Laminar View Post
Some parts were beyond help, in which case I had to shell out $$$ for OEM-spec replacments:
So, what do you do when the new parts don't have the same config as the old? (do you need the two holes in the original?)
     
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Mar 2, 2014, 03:18 PM
 
The bracket attached with a single hole on back, so I was able to pull the old bracket, clean and paint it, then attach it to the new horn.
     
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Mar 7, 2014, 12:07 PM
 
edit: The server ate the first half of this post, I'll have to come back to it.

Boring out the cylinders means new pistons and rings. The two main piston manufacturers for these old triples are Wiesco and Wossner. The Wiescos are popular but a few people have had issues with premature wear and poor performance, so I went with the forged Wossners, really a beautiful piston.




As far as the cylinder heads themselves go, I decided to try out some glass bead blasting. I cut up and old tupperware container and got a glass bead blast gun. The initial results were pretty good! Before on the left, in progress on the right:


I cleaned up the underside of each head, but was careful not to blast the combustion or mating surfaces:


Here are the cylinders installed:




And the heads:




Next up...continued assembly!
( Last edited by Laminar; Mar 9, 2014 at 08:37 AM. )
     
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Mar 9, 2014, 07:46 AM
 
Wow, glass beads worked well; those are great. No kidding about being a restore - looking frigging mint at this point. What did you use for the paint?
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Laminar  (op)
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Mar 9, 2014, 09:13 AM
 
It looks like the server's working again and I'm stuck in Frankfurt for the next few hours so I'll try and recreate what I lost before.

With the engine cases completely broken down and cleaned out, I hit them with some high temperature paint.


Masked:


Painted:


This paint requires specific heat cycling to properly cure. I put each half in the oven for 30 minutes at 450, 500, and 550 degrees with a 30 minute resting period between each temperature. Wife was not please when she came home to motorcycle parts in the oven. But they looked great after baking:




Next up came rebuilding the transmission. To make sure it shifts properly and doesn't pop out of gear under throttle, the spacing between all of the gears must be set very precisely. I disassembled both transmission shafts:


And was able to find some NOS Kawasaki transmission snap rings and shims:


Everything was assembled, placed in the upper case, then measured. After a few iterations, the spacing was correct and it shifted smooth as butter:


I think I mentioned before about how these crankshafts are very special - only a few people in the world have the knowhow and tools to correctly rebuild them. So I shipped it off to Maryland for rebuilding, where the guy informed me that my rods were pretty pitted, so those should be replaced, too. Cool, more $$$. I think all in all, the crank rebuild alone ran me ~$1000, which is more than I've spent on an entire bike. But it turned out pretty good.

Crank before:


Crank after:


Note where there used to be rubber seals separating each cylinder, there are now aluminum labyrinth seals...much sturdier!

So now the crank could be installed into the upper case along with the kickstart shaft:




     
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Mar 9, 2014, 09:13 AM
 
The lower case was put in place and torqued down:
November 8, 2010




And because the engine would only get heavier as more was added to it, I went ahead and put it in the frame:




Here the clutch is installed:


And the clutch cover:
     
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Mar 9, 2014, 09:15 AM
 
Originally Posted by ShortcutToMoncton View Post
Wow, glass beads worked well; those are great. No kidding about being a restore - looking frigging mint at this point. What did you use for the paint?
Paint on the frame was Rustoleum semi-gloss, paint on the engine cases I don't remember exactly, but I think it was VHT.
     
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Mar 14, 2014, 11:54 AM
 
After that confusing turn of events, back to work.

Now that the engine was back in the frame, it was time to start cleaning up and reassembling the rest of the bike.

Here the ignition coils are placed in the frame and attached to their spark plugs. I also ran the wiring harness down the length of the bike:


Here's some assembly of the controls and gauges. The new cables are installed, too:


I went ahead and threw the wheels and old tires back on the bike so that I could roll it around again:


November 14, 2010
Then I installed the exhaust pipes, the headlight bucket, and the turn signals:




Now it was time to get the carbeurators cleaned up. When I got the bike, the carbs would leak like crazy and dump gas out onto the engine...no good! Here are the three carb bodies:




Undergoing disassembly:


Solvents are great! The float and bowl on the left were full of a gasoline/Seafoam mixture. The items on the right just had gasoline. Big difference!


Unfortunately the carb cleaning wasn't without its setbacks - one of the tiny brass jets basically disintegrated in its deep setting and required replacing the carb body.


Looking clean:


I went ahead and installed the carbs along with the new intake manifold and the repainted airbox:


I set the tank on top to get help get me motived to keep at it, late November in the garage gets cold!:
     
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Mar 18, 2014, 08:01 AM
 
It's time to finish up rebuilding any accessories. First off, the front brake. I painted the master cylidner a while back:


But it leaked quite badly. So it's time for a rebuild! Disassembly requires three hands, or two and a carefully placed steel rod:


I'll let you figure out which is old and which is new:


With a new sticker up top it could be installed on the handlebar:




Since the master cylinder was new and shiny, why not the caliper, too? Actually, when I went to bleed the caliper for the first time, the bleed screw snapped off and ruined an easy-out when I tried to extract it:

     
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Mar 18, 2014, 08:02 AM
 
So that caliper half was trash and I had to find a replacement on eBay. I got the replacement cleaned up and painted with some hammered-finish paint:




March 23, 2011
With the brakes good to go (well, at least as good as a 30+ year-old single piston caliper will ever be), I focused on the seat. The edges of it showed all sorts of rust:




So I pulled the cover and padding off of the pan to find this:




March 31, 2011
Like every other part for this bike, seat pan replacements are impossible to find - they often rust out and no one makes reproductions, so this one had to be salvaged. I attacked the surface rust with a wire wheel and hit it with some Rustoleum Rust Reformer to protect it for now:


*quick break to buy a house and get moved*


June 27, 2011
Back at it in the new garage. I used some electric shears and cut out approximations of what the seat pan sides should be like:


Then I used an angle grinder to cut off all of the rusted material:


And welded the new strips of metal in place:




July 6, 2011
If you look closely, you can see the spikey teeth strips welded in place to hold the seat cover:


Painted:


Black edging added to protect the seat cover from the sharp metal edges:


With a new block of seat foam and a new accurate reproduction seat cover, it will look great. But that's coming up later.
     
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Mar 22, 2014, 03:30 PM
 
So let's talk about getting this bike running again. This was the first engine I ever rebuilt. I've brought dormant engines back to life plenty of times, but never actually pulled everything apart for a rebuild. So once the bike was rolling on its own and the engine was in the frame, I hooked up the gas tank, poured in some 91 octane, and kicked it over.

WARNING: This video contains way more of my backside than anyone would ever want to see. But it was hot out and that's the undershirt I happened to be wearing that day. This truly was the first time the bike fired, so I was much more concerned with how it ran than which of my crevices was appearing on camera. With that said, here it is:

https://www.youtube.com/watch?v=mkRQc1HQY_U
     
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Mar 25, 2014, 04:53 PM
 
Let's finish this up, shall we?

Now it's time for paint. Because I was keeping the bike as original as possible, I want to stay true to the original metallic red/maroon paint job. There are a few guys in the US that specialize in this type of paint, but every quote was for a minimum of $700, and some were more than double that. I figured I could make it work on my own. The original paint job consisted of four layers:
1. Gloss black base coat
2. Metallic speck
3. Candy color
4. Clear coat



A few areas of the bodywork had been protected from the elements so I could see what the original paint looked like:


After sanding down what was left of the original paint, everything got several coats of primer:




Then the gloss black base coat:






Then the metallic speck:






Then the candy red:






After the candy went on everything got wet sanded:
     
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Mar 25, 2014, 04:54 PM
 
June 6, 2011
And finally the clear:






As you can see, the lighting and angle really affect what color everything appears to be. But the clear had a lot of orange peel still:


Time to fix that! I wetsanded the clear with 1000 grit and 2000 grit, then finished it off with two different polishing wheels. Final product:


And after a coat of wax:










June 10, 2011




Nothing left to do but put everything back together and get it fired up!
     
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Mar 25, 2014, 05:06 PM
 
Put back together in the garage with new bodywork:
https://www.youtube.com/watch?v=c7XNjyb1nho


Installed the rebuilt seat, just waiting on the replacement headlight.




Got it!
July 29, 2011








https://www.youtube.com/watch?v=QK4-K_9noYc
     
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Mar 26, 2014, 10:36 AM
 
very shiny! it just started right up after you put it back together, that sound must have been rewarding.
     
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Mar 26, 2014, 12:45 PM
 
It's always a great feeling.
     
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Mar 26, 2014, 02:03 PM
 
damn that's a shiny looking bike there. great work!
     
   
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