Kawasaki kz400 - mini superbike

I have been considering another bike project for an occasional ride with old motorcycle friends. I didn't want anything expensive and one of my favorite bikes that is kinda unloved is the Kawasaki kz400/kz440. I've owned and tinkered on a handful of them over the years so I know them pretty well. For months I've been waiting for the right deal as I'd like to somewhat recreate a bike I built that was stolen years ago. It was a pile of various kz400/kz440 parts I pieced together along with some other Honda cb350 bits.

So last Wednesday I noticed an ad on the old Markets with what was listed as a 78 Kz400 for $300. I sent a message asking about title and he says nope. Not too difficult to get one and the price is low enough that if I was forced into a bonded title it wouldn't sting much. Then I notice the price dramatically dropped to $100, so I looked at the ad again to see what I was missing. The plugs weren't threaded into the head so I asked if it was locked up. I figure he just left it out and water got into the cylinders. He says "I took it to a shop for some minor repairs... They blew the engine". Yikes. I figure I can use what's there and track down a kz440 engine to drop into this frame super cheap. A little bump in power, not much money invested, and the rest of the bike has what I want for the most part. So the next morning I head out to Joplin MO about an hour away in hopes I can fit it in the back of my Montero.

The guy was super nice but wasn't mechanically inclined. He poorly painted lots of parts with black paint overspray everywhere. Janky clubman style handlebars were loose. Wiring has been hacked with. Part of the tail/cowl bracket has been cut away. Carb boots are cracked pretty good. Carbs themselves look like they were definitely tinkered with but used vice grips or something to do the work. Seat pan is in good shape but the cover is pretty tore up. All in all it's a project and for $100 I can't say no as the frame and most of the bits I need are there.

He said the "mechanic" he had taken it to was supposed to get the carbs running right and then when he got it back it had no compression. I thought that's weird so using the kicker it pushes through with zero compression. I can't hear or feel the pistons moving or crankshaft itself. Something is up for sure. After paying the man and filling out paperwork I noticed the clutch lever was zip tied to the handlebar grip. Oddly enough I noticed this in the ad pics but never put much thought into it. Instead of clipping it off in front of him I waited until after we loaded it to investigate further back at the house.

The bike sorta fit in the Montero. I had to ratchet the back door to make sure it wouldn't swing open but there was enough space to let exhaust gas through. All windows were down the whole ride home but still got a whiff every now and again. I made it home without dying and a mild headache.

Here it is unloaded and sort of reassembled.

After loading the bike up I just couldn't wait to see if the zip tied clutch lever was keeping the crank from engaging with the kick starter. I didn't want to do this in front of the seller and rub it in his face, so I drove straight to the nearest gas station to see. Sure enough, we gots compression!

Now the bike is still rough but hard to beat what I have for $100. The tires are in goodish shape. Exhaust is surprisingly not hacked up. Forks and brakes appear to be serviceable. Chain and sprockets look like they have low miles.

Friday morning I had time to tinker so I started with the rear wheel and brakes. The brake lever itself was pretty stiff and looked like the pivot could use some lubrication. Before you know it I've cleaned off some hardware from overspray, lubricated the brake pivot, swingarm pivot, axles cleaned up, greased bearings, cleaned up the brake drum surface, sprockets, etc. The rear brake needs readjusted but everything is now moving like butter now. The chain looks to be in great shape so it's soaking in kerosene to get cleaned up a bit.

As mentioned before there was a bracket cut off the frame that the cowl bolts to. The PO had it in the box of parts so I used the flux core glue to get it back where it belongs.

After a few hours of work I had to call it quits. Since it was mostly a greasy dirty job I didn't take many pics. I'll be tackling the front end next or stripping the hacked up wiring, not sure yet. Probably a bit of both.

Grand plan time. As mentioned in the thread title, I'd like it to resemble or be a mini superbike of sorts. I always dug the old Moriwaki Kawasaki's so this will be an homage to that with some other style cues of the era. I'd like it to perform better than stock, but I have no grand illusion this will function to the level of any litre bike of the last few decades. Just a weekend canyon shredder.

I need a new master cylinder as the one that came with the bike doesn't have the cover for it. Based on my experience an 11mm master will give the best feel, which most dirtbikes happen to run. I'd prefer to buy new so I'll probably keep digging around the internet until I find the right one at the right price.  Possibly lighter front rotor and modern caliper adapted if I manage to find something that will be within my wheelhouse.

I've been a fan of the Superbike bars from Emgo so I'll probably just use them like old times. Oury grips or similar.

Maybe a digital cluster of the smaller variety for tach and speedo.

Wheels and tires are still up in the air. What's on the bike will work fine for now but I'd like to get some wider and lighter aluminum hoops laced up. Buchanan's has what I need and since the initial purchase price is so low I won't feel bad spending the money. Probably a 19x2.5 or 18x2.5 up front and an 18x3.5 rear but need to measure and make sure I have space needed with the stock swingarm. The previous bike had mag wheels which were super low maintenance but insanely heavy.

Rear suspension will probably be some Hagon shocks, but maybe I'll get the spicy Worxs or whatever the newest good stuff is these days.

Front suspension will probably be some Progressive front springs and some other tinkering I've done previously that has helped quite a bit. The forks aren't all that beefy at 33mm but with a brace and internal work it should do fine enough for me. If I get fancy with the rear shocks I may get a set of gold valve emulators to help get a good balance.

The seat obviously needs recovered but I may reshape it a bit to get it where I like it. Stock they are pretty stiff and on longer rides a bit uncomfortable.

The gas tank is a mess. The guy tried sealing it and somehow there is a huge floating chunk of the stuff that I haven't managed to snake out of the opening yet. If I find something else in better shape I'll probably skip the hours of work to get this one where it needs to be. I may find something else that I like better in the looks department but would be nice to keep it simple.

The electrics should be easy to sort. I'll build a new harness and since it has a kickstart that will let me simplify the whole thing. The starter will be pulled and this will allow a lightweight battery.

Maybe at some point I'd like to reduce the sprocket/chain combo down to a 520 size for weight but for now I can focus funds elsewhere.

Exhaust will probably stay as is, maybe some bolt on mufflers at some point?

Points and condensor for now, but maybe an electronic ignition at some point.

Carbs may just stay stock with a full refresh if possible. I'd like to do Mikuni VM round slides but tuning these will take a lot of time and effort. Unfortunately I don't have the stock airbox and these CV carbs with pod filters don't really run well no matter how they are tuned. It's one piece I'm missing so gotta consider that.

That's fantastic!

I've daydreamed occasionally about doing pretty much exactly this with this bike with the hope of making a kart track superbike...

In reply to Jesse Ransom :

It fits the profile to do it. I'd like to take the finished article for a track day at Hallett but trying not to get too far ahead of myself at this point. I've previously wanted to put together a standard recipe cb350 race bike but they feel so tiny compared to the kz400. I need to look at the AHRMA rule book and see if anything I plan will work into their classing structure.

Cheap old bikes call my name. I ignore them. But my resistance is getting weak.

I'm going to try and just tinker a few minutes whenever possible on this. Last night I stripped the handlebars, gauges, and wiring to get a good look at the mess. Definitely need a new harness. Cables are on their last breath. Headlight isn't stock, not sure of it's origin but I prefer the original so I'll need to track one down.

I bolted the stock bars back to the risers and took a good stare.

What to do next? I didn't want to get into the forks yet so I pulled out the compression tester to see what we were dealing with.

Both ran up to about 150 on the gauge per cylinder on the first test. Which is about what a stock showroom bike should read. Then I retested and show 180ish on each. My guess is the gauge isn't super accurate but at least it stayed consistent. My leg was sore from kicking so much so I called it a night.

Not many $100 bikes around these days; despite condition I'd say well bought. I loook forward to seeing your progress!

That's great compression. Hard to go wrong with that project at that price. 

That was worth the 3 bills, even if the compression was not such an easy fix. I've always liked the older smaller bikes. I just don't really fit on them, anymore. 

A little more tinkering last night. The PO said the starter wasn't working if I remember correctly but I think that was due to the terrible harness. I hooked up the battery and jumped the solenoid. Rolls over no issues but the battery was pretty low so only a few goes before it went flat. Either way I'll probably ditch the starter since I have a kicker and these bikes have never been difficult for me to kick start. Famous last words?

Anyway, I pulled the starter finding a good amount of mud/dirt below. I think the bike was a haven for mud dobbers at some point. To pull the starter meant pulling the left side cover. I couldn't remember if this was in oil bath or not. It is. Luckily I put a pan underneath to catch it.

I remembered to check the odometer for mileage. Forgot it was silly low if correct at 2699 miles.

Here's where I left off.

I've been doing research on what rim size makes the most sense for proper handling but also some vanity. Bikes that look cool are pretty neat, but lots of stuff can make the bike worse than it ever was stock. I think I've narrowed it down to 18x2.5 up front and 18x3 or 3.5 out back. Tires will be Continental Classic Attack vintage with either a 90/90-18 or 100/90-18 up front. For the rear would be a 110/90-18 or 120/90-18. I spent some time measuring for tire to chain and swingarm clearance as that's the area I'm most likely to find issues. I think either one will fit just fine. I also recall the 440 LTD swingarm being of the beefier variety. From light reading it's a hair under 2" longer. Not sure I want to lengthen the wheelbase any yet, but I've confirmed it can fit easily. More reading to do on that.

I'm also fairly certain I can bolt on a set of 440 jugs and pistons. The heads are the same. There are quite a few pretty cheap on ebay. I may save that for later down the road but the poorly painted top end could expedite it real quick like.

I've been missing my 79 KZ400h LTD that I built, learned to ride on, and got my license on. Never thought I'd ever own a bike no less build one from nothing. It was leaning against a tree with a "free" sign on it. Of course I knew nothing about bikes, but was annoyed at watching the idiots at OCC build bikes so I figured why not. It was missing a lot, but I found a used 440 with most of what I needed. Should have taken the electronic ignition but didn't know I'd want it. It was sooooo smooth and felt great to drive.

In reply to vwcorvette (Forum Supporter) :

I like how you did the seat and tank on that one. I'd consider switching to the factory electronic ignition but I worry at this age it may kick the bucket at the worst moment. There's a guy who managed to make a GM HEI ignition work using factory points. I may look into that at some point.

Can I come play with my RD400 F?  Dude you hit this outta the park.....love it

In reply to captainawesome :

The seat was an ebay buy. Slips on and off super easy for access to the battery. The tank was dented by a previous owner's knee. It was hidden under metallic purple paint and about an inch of Bondo. I cleaned that all off and dented the other side to match!

Did I mention I miss this bike?

I like where you're going with yours.

In reply to vwcorvette (Forum Supporter) :

I'm hoping this one turns out better than my first attempt. I think it will, but I haven't ridden in a few or more years now.

In reply to 759NRNG :

Pics of the RD? I've owned a few basket case R5, RD350, 400s over the years that I never got around to even starting. For some reason I was always intimidated by the crank bearings.

Been out of town for a week but got a few minutes last night to tinker. I managed to get the carb holders off the head without much fuss. One screw head turned to butter but a pair of vice grips managed to remove it just fine. I also took a few minutes to measure the screw length to order stainless allen head hardware. Then I went back to the gas tank to try and fish out the massive chunk of sealer floating around. It was a royal pain in the ass. I managed to get a hold of it good enough to drill some holes and try to break it up into pieces. The process actually took a few hours patiently getting the piece where I could either grab with needle nose pliers to break up or keep drilling holes while holding the tank upside down and not actually drill the tank itself. It sucked. I came out victorious however so it's one job done.

Here's some of what I managed to yank out.

In reply to captainawesome :

That's really gross. Even though I only rode for a couple years, I really do miss having an old bike around. 

In reply to AxeHealey :

I hope I end up using it at least a few times a year. I doubt I'll ride as much as I used to but it will be nice to have something to get out into the Ozark Mountains again. Lots of excellent roads to ride. Would be fun to do another road trip as well.

In reply to 759NRNG :

I had a RD400 for about a month (while rebuilding my chopper - common theme in my scooter stories) back in 84. Super fun bike. 

That looks like a fun project. Can't wait to see it on the road.

Got a little tinker time over the weekend.

When kicking the bike over to test compression it was obvious I needed the rubber on the kick lever back. It was missing when I purchased the bike, so ebay to the rescue. It was a pain to install being an older NOS part but I managed to get it squished on there.

I also received some new parts to swap out. I've always liked the handlebar risers from the early Yamaha bikes since they were roughly only  1/2" rise versus most around an 1" or so. These still need cleaned up and painted but were just the thing I was looking for.

And then of course it's time for the superbike bars, Oury grips, and an 11mm master cylinder. Still need the throttle assembly but that's all in the works. I normally trim the big lip off the inner side of the grips since they look more motocross than street, just didn't want to rush it and botch the job up.

I'm pretty happy with how things are shaping up. Still a lot of work to do as this is just simple dress up stuff but it's a good motivator.

A little more tinkering while I wait on some parts. I replaced the soft JIS side cover screws with some stainless allen heads. Now if I do some roadside repair I don't have to worry about stripping them out. Also anti seize was used since it's aluminum and stainless which don't play nice together.

I also received the tail light and got to installing. It's an Emgo brand that mimics an older Lucas version. The stock one is HUGE and has all of the turn signal brackets which are huge as well. This is tidy but still bright enough to be seen when going down the road. A few holes drilled and voila! It's on.

Love your build! I had a '78 Honda CB400TII Hawk with similar bars etc. that I rode across country when I was 18 back in '81....it was a great trip!