'78 KZ400

[alemonkey]

I've never built a bike before but always wanted a cafe, so when a friend of mine offered up a '78 KZ400 I jumped on it. He bought it on auction a while back but never got around to fixing it up. It's dirty but it runs and was in decent shape. Everything is straight, the mufflers have been replaced by aftermarket ones and the tank appears to be a NOS replacement. It looks like it probably sat in a barn for the last 30 years or so until someone dug it out and tried to get it running. Only 3900 miles! Tires are brand new also, still have the nubs.

Hopefully I can recover a little cash by selling off the seat, side covers, luggage rack, etc. One of the saddlebags has a hole (although I have the piece and it could be repaired).

To be a little different I decided to go with a single carb intake from 11th Hour Industries and a Mikuni VM34. So I'll be trying to sell the factory carbs and airbox, also. One weird thing is that even though this is titled as a '78 it's actually a '77 frame and motor and was built in September of '77. The pre-78 frames have a center post right behind the motor, so a single carb intake for those frames has to exit out to the side instead of straight back.

 

[alemonkey]

Started tear down. I'm hoping to get everything fabricated and have a rideable but not finished bike some time next summer...then next winter hopefully take it down to the bare frame.

Test fitting a rear hoop.

Mikuni VM34 mounted. Waiting on a new petcock for the tank before I try to fire it up.

 

[alemonkey]

Cut a bunch of brackets off the frame today, welded on the rear hoop, and ordered a Mac 2 into 1 exhaust. Petcock still isn't here. Once that shows up I'll try to get it running with the Mikuni, but since the exhaust is going to be changed I won't worry about tuning it yet.

Next weekend I'll run out and get some closed cell foam to start making a form for the seat. It's been a while since I've played with fiberglass so this should be fun. I also need to pick up some sheet metal to make a tray under the seat for the electronics. Haven't decided what I'm doing with the battery yet...if I can get away with it I'd prefer to not put it under the "hump" because I want to make two seats eventually, one of them a 2 person.

 

[alemonkey]

So....I screwed up. I've been grinding tabs off the frame and doing a ton of sanding to smooth them out, but I forgot that I had the crankcase breather hose disconnected. After a couple hours of grinding I noticed that the area around the breather tube was covered in grit and I probably got a bunch down inside it. So, I guess I should pull the head and clean everything up before I start it. I needed to do that anyway because the head gasket is seeping oil. Oh well.

 

[bcnSR250]

That sucks about getting all the crap in there, good luck with the build.

Sent from my phone at a place via an app

 

[alemonkey]

Yeah, I was going to tear it down anyway so it's not a big deal. I just feel stupid

Wondering if I should put new rings on the pistons while I have it apart. I've heard the guide for the timing chain tends to wear on these, too, so I'll take a look at that.

 

[doc_rot]

You may find that the head leaks even after replacing the gasket. I have never seen a early model 400 motor that didn't weep a little oil.
What condition is your caliper in? If it needs to be rebuilt there are no parts for it so you have to swap for somethings else

 

[Nebr_Rex]

You may find that the head leaks even after replacing the gasket. I have never seen a early model 400 motor that didn't weep a little oil.
What condition is your caliper in? If it needs to be rebuilt there are no parts for it so you have to swap for somethings else

That's why I went with the 440.
But I've thought of tinkering with one to see what I could do to address the oil issue.
And .... maybe a resleeve to 69.5mm and the 440 6 speed .......



.

 

[doc_rot]

That's why I went with the 440.
But I've thought of tinkering with one to see what I could do to address the oil issue.
And .... maybe a resleeve to 69.5mm and the 440 6 speed .......



.

dry block

 

[alemonkey]

dry block

Now that's cool.

 

[alemonkey]

You may find that the head leaks even after replacing the gasket. I have never seen a early model 400 motor that didn't weep a little oil.
What condition is your caliper in? If it needs to be rebuilt there are no parts for it so you have to swap for somethings else

The caliper looks good, as far as I can tell. Doesn't seem to stick.

 

[alemonkey]

Good news, I pulled the crankcase breather off and found there's no way any grit would have gotten down into the head. I had assumed the breather was directly plumbed into the valve cover, but it's actually in it's own cover on top of that. Plus, there's a baffle under it that would have prevented anything from getting in. I looked in the area under the breather cover and it was completely clean. So, I'm going to hold off on pulling the heads until I'm ready for a complete teardown.

Started on the form for the seat today. Needs a little more sanding, then I'm going to cover it with duct tape and start glassing. Snapped a pic before I did any sanding. It's slimmed down a lot now.

 

[adventurco]

Packing tape works very well along with a few coats of release wax to coat a foam plug. You will be able to pop the glass right off the mold without damaging it.


Sent from my iPhone using DO THE TON

 

[alemonkey]

Good idea, packing tape is much smoother. I have a feeling that the little lip at the front of my seat pan is going to be pulled off no matter what when I separate the plug from the fiberglass. It's pretty thin. Not a huge deal, since I only need to make one. I hope. ;D

 

[alemonkey]

First coat of glass on the seat. Couldn't get my camera to focus worth a crap for some reason. It used way more resin than I expected, going to have to buy more.

 

[alemonkey]

Well, apparently the epoxy I used on the seat had gone bad. It sat for a week and never hardened up, so I stripped it off and reapplied with polyester resin this time. Much better. It needs some trimming to get it to fit up around the tank and a lot of sanding to smooth it out, but I have a seat pan.

Need to figure out if I'm doing clip ons or clubmans.

 

[alemonkey]

I also built a battery / electronics tray. It hangs down about 1.25 inches below the frame, so combined with the hollow area directly under the seat I have a little over 3 inches of depth, which should be enough to fit a lipo battery. Gave it a quick coat of primer to keep it from rusting over the winter.

I have a Rick's regulator/rectifier on the way. I was surprised they actually make one for this model that's plug & play. I figured I would have to wire up a universal one.

 

[alemonkey]

Getting closer on the seat. I've found the hard way that creating something perfectly round is pretty hard. I keep finding low and high spots that need filler or sanding. I'm pretty close, though.

I welded some tabs to the frame that the seat will attach to, but forgot to get pics.

Decided to go with drag bars for now, as my wife also wants to ride this bike and she wanted something more comfortable than clip ons or clubmans. Stuck them on tonight to just see how it looks. Next big project will be to replace the leaking fork seals. Gotta get some smaller gauges, those factory ones are huge.

Can't decide if I want to fabricate a new front fender or keep the factory one. It's pretty much in perfect condition so I'm not going to cut it up.

 

[The Limey]

Keep it, has a nice period look with that stay on it.

 

[stroker crazy]

The drag bars will be less uncomfortable than clip-ons with the standard footpegs.

Crazy