75' KZ400 Build (pics and vid heavy)

About a month ago I bought 2 75' KZ400's for $300... after kicking the kick-starter to pieces on the red bike, I got it to fire up on 1 cylinder. The red bike is a drum brake, kick-only, the blue bike is a disc-brake electric start that is rusted to bits and the engine is sealed up with some sort of white/off white sealant...



Because of this I'm moving forward with the red bike, there were only 5k miles on it compared to the 8k on the blue bike.

Long story short. I want to make it into a dual-sport, scrambler build.

First things first, I ordered up an entire engine rebuild kit, gaskets, seals, bearings, rings, valve seals, all the good stuff to get it back to "like new" condition... THEN I did a compression test, and saw it had 100psi on both cylinders dry, and dead cold... so I figure, maybe a full re-build won't have to happen. I'll just get it running, maybe go as far as removing the head to clean up any carbon, but not go super deep into it for right now.

So second thing... carbs. Did a complete tear-down and rebuild. The right carb was completely gummed up, but I made quick work of it by boiling the bodies in Lemon Juice on the grill for about 20 minutes a piece. I then went to town on the buffing wheel.







After that, I took to stripping the bike down completely...




Once I got it down to the frame, I marked all the tabs I wanted to chop off, and set to work. I'm wanting to run high-pipes on this bike, so I lobbed off the passenger peg/exhaust brackets, and shortened the one on the brake side with a little plug to ensure the brake will operate like normal... I didn't want to re-engineer the brake spring and all that jazz.










Now that the frame is squared away I'm going to hop onto the exhaust... using the donor (blue) bike as a template, I will take the 4 stock head pipes that I have and see if I can't fab up a 2 into 1 collector that goes along the right-hand side of the bike.

I plan on using the stock rear-fender and seat, but simply re-positioning the rear fender to give a bit of a "duck tail" look... something close to this:




Should bolt up pretty straight forward.

Here are 2 of the videos I have so far, will post more as they're uploaded.

Video up later this week, but I've been BUSY.

I bought a .50 cal ammo box from a local Army surplus, and quickly fab'd it into a battery box. I welded on a cross bar and a tab at the front to allow for 3 bolts to hold the box into the triangle. There's JUST enough room inside for the battery, solenoid, regulator, and fuze box with connections... the rectifier will reside outside the box.










While I was at it I also extended the left-side mount on the swingarm for the shock. The shocks I'm using run VERY close to the chain, so this gained me about 3/16 clearance. More than enough.

Sorry for the double pic in the last one, hard to figure out this forum... haha.

Anyway, I was able to get the frame painted, and just threw a quick flat-black on the battery box to prevent rust while fitting it. It's going to eventually get body work and may possibly end up the same color as the tank... maybe. What's cool is apparently VHT gold is a dead ringer for the gold on my shocks.












While that was curing up, I threw a couple good base coats of semi-gloss black onto the engine. I had to give this thing a really good scrubbing before hand. Simple Green, Brake Kleen, and finished up with some Dawn... but it took a LOT to get it ready for paint.

Putting these motors into the frame is terrible. Luckily I got it done with minimal dings (masking tape helped). But, the frame-over method worked out well... have to take the breather cover off, and get the motor at about a 90 degree angle in the rear of the frame before you can twist it around.

Anyhoozle. Got the motor in, and removed all the cases for letter polishing and paint. I wanted to keep polishing to a minimum on this bike. Timing cover, tappet covers and inspection port screws, and lettering was all I wanted.










My new tires also came in... going with 3.50x18 Kenda K270's front and rear. 50/50 dual sports. The wheels will be painted black, hubs and spokes only, the chrome rims are in great shape, so a good buffing will bring them back to life.

As you can see in the last post, it was an EASY swap to stick the starter, clutch, and chain into the non-electric start bike. The cover studs are a little hard to get out, but vise grips are your friend.

I had a small crack in the case, merely a pin-hole. I'm assuming it's from the brake pedal hitting the case. To tell you the truth, I didn't even notice it from the out-side. Anyway, a quick bit of brazing, and she's good as new.





The cases are going to be wrinkle finish. So I set to do all the polishing work first, then a lot of cleaning, and masking. They didn't come out too bad! I did go back and hit the background of the lettering with some flat-black, then polished up the letters with a little mothers metal polish.








Re-installed the clutch... everything was in spec... not bad for a 5k mile bike that's been sitting for nearly 30 years. Plates, discs, and springs all went back in... I'm also testing out the blue tank here, just as a color pallet.









So far, not bad. More to come!

Really nice work. That is going to turn out great.

Cool; I had the same ding in the case of my KZ400 motor. it's as thin as an eggshell.
After welding, mine still leaked slightly; there was no tig or mig available, it was welded with an open flame, flux, and rod.
I solved the problem with permatex painted on the inside.
Changed it to monoshock. 100w halogen headlight, added high + low relays. No other mods.

Love the wrinkle paint.

I just sold all my leftover KZ400 parts the other day; nostalgia fills my soul.

Nice machines in your shop; I also dabble a bit, got an little old lathe and a big drill press but no mill.

Looking great! Yup, my buddy's Kz400 had the same ding in the clutch cover from the brake pedal. We brazed it with Alumaweld. Ugly, but worked.

Sweet mate, that is going to be mint!

mark in Portugal wrote: Cool; I had the same ding in the case of my KZ400 motor. it's as thin as an eggshell.
After welding, mine still leaked slightly; there was no tig or mig available, it was welded with an open flame, flux, and rod.
I solved the problem with permatex painted on the inside.
Changed it to monoshock. 100w halogen headlight, added high + low relays. No other mods.

Love the wrinkle paint.

I just sold all my leftover KZ400 parts the other day; nostalgia fills my soul.

Nice machines in your shop; I also dabble a bit, got an little old lathe and a big drill press but no mill.

Yeah, we got some nice toys to play with haha... it'd be even better if I could use them to their full potential.

loudhvx wrote: Looking great! Yup, my buddy's Kz400 had the same ding in the clutch cover from the brake pedal. We brazed it with Alumaweld. Ugly, but worked.

That's what I used... Alumilux/Alumiweld... seemed to hold just fine. Hit it with a flapper-paddle to smooth it and then the wrinkle paint hid the majority of the sins.