78' KZ400B - another rabbit hole.

canyoncarver

'hacking is learning'
Awhile back I picked up a 1978 KZ400B with a spare 76' 400 motor for cheap. It's another rabbit hole, thus the name. It was registered and running as of late 2016 then supposedly stopped running and sat. The po apparently lost or sold off a few parts like the tank, coil, left foot rest, and shifter among other things. The engine turns but I haven't gotten as far as trying to fire it up. I'm doing the homework on it now and trying to decide if I want to sort it out.
 

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canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

Nebr_Rex said:
Rear sprocket is also incorrect. Should be 15/45.
Not the least bit surprising so far. Chain and sprockets are toast anyway. My focus right now is figuring out the differences in the various engine versions. What I have vs, what I'd like to have, etc....

I've been reading kz400.com and also found some good info on kzrider. A good bit of it were your posts on these bikes. All input is welcome and appreciated.

I'm hoping the bottom end on this one is good. It shift correctly on the lift at least. If it works out, I'd like to do the 440 head upgrade at some point. End goal would be a nice streetable rider with some extra oomph over stock.
 

canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

advCo said:
I dig it. Bring it back!
...but finish the 750 first ;)
Yeah, now that I've got one of my YZF750R's reasonably sorted out I want to get back to the 750 twin. But hey - SHINY!
 

doc_rot

Oh the usual... I bowl, I drive around...
DTT BOTM WINNER
Re: 78' KZ400B - another rabbit

As a big Kawi fan, and having owned a 78 kz400... I would pass. Nothing particularly bad to say about them other than they are boring. not enough power, "good enough" handling, could barely keep up on the freeway. I am a big dude (240lbs) so YMMV. I remember taking that kz400 out for its first ride after spending a bunch of time completely going through it that winter and sadly realizing I would sell that bike immediately. glad I did, thats a nap on wheels. I would focus on your 750 if you want a kawi twin. just my $0.02
 

canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

doc_rot said:
As a big Kawi fan, and having owned a 78 kz400... I would pass. Nothing particularly bad to say about them other than they are boring. not enough power, "good enough" handling, could barely keep up on the freeway. I am a big dude (240lbs) so YMMV. I remember taking that kz400 out for its first ride after spending a bunch of time completely going through it that winter and sadly realizing I would sell that bike immediately. glad I did, thats a nap on wheels. I would focus on your 750 if you want a kawi twin. just my $0.02
Yeah, my 750 twin is in the corner, staring at me.

I appreciate the input. That's why I posted this. Haven't really been able to make up my mind.

I'm a big guy also, it sounds like we are about the same size Doc. I was half thinking of setting it up for my wife and maybe daughter but its turning out they just aren't that interested. I never figured it would be any good on the freeway. I can see a neat little in-town city bike in my head but it needs quite a bit of work to get there. I have very little in it at this point so I might even make a few bucks if I flip it. I have a KZ200 single that I finally decided to sell for similar reasons. Maybe flip the 400 and keep the 200? Dunno... I have the itch to see if it runs though.
 

canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

Found a coil in my part shelves to test with and I got new spark plugs. I'll have to modify the harness a bit. I also haven't adjusted points in over 20 years....

I haven't thrown in the towel yet.
 

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canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

john83 said:
Might as well see if it runs at least.
Yep. It' would eat at me otherwise.

I think I've decided not to sell it for awhile. I still have the spare motor, it's an earlier version but it's "supposedly" out of a running bike. The po believed the motor locked up so they got the spare but never did the swap. It was so cheap I didn't question it and just loaded it up. I got it home and it turned by the kicker just fine, feels like it has compression. I suppose I'll find out whats up when I finish prepping to start it.
 

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freemonty

New Member
Re: 78' KZ400B - another rabbit

I’ve gone through a full resto, top end rebuild of a 76 Kz400, so if you do end up doing it and have a question I may be able to help.

I have to agree with one of the earlier responses though. You could spend thousands and do all the modifications in the world but you’ll never be able to squeeze the horses out of these motors to make this bike exciting. Trust me I’ve tried. One day I’ll explain this in my unfinished build thread...

That doesn’t mean I’d sell it though. It’s a reliable, easy to work on bike. I think a tracker build would work if you lightened the piss out of it.

Here’s mine:
KZ400 Resto-mod
https://r.tapatalk.com/shareLink?share_fid=9366&share_tid=74009&url=http%3A%2F%2Fwww%2Edotheton%2Ecom%2Fforum%2Findex%2Ephp%3Ftopic%3D74009&share_type=t
 

freemonty

New Member
Re: 78' KZ400B - another rabbit

Oh god that pictures awful. That’s not the finished bike! How does it decide which picture from the thread is going to be used for the thumbnail
 

Nebr_Rex

Member
Re: 78' KZ400B - another rabbit

There is no need to swap heads. The only difference between the late 400 and the 440 is
bore size, cam chain and kick start. The thing that holds the KZ400/440 back is the cam timing.
Intake lobe center is 113*. The cam needs to be advanced. KZ900/1000s are 110* from the
factory and some have degreed them down to 102*. KZ650s and KZ750s are 105* and that is
what most street racers set their bikes to 'back in the day'.
The 440 head flows very well. It is a scaled down version of the GPz1100 Unitrack. The only
thing it would need even for a mildly modified engine would be a little clean up for core shift.
Cam chain on the 400s is a roller and a Hyvo for the 440. There are ways with both of
these to advance the cam with no machine work. As for carbs most people use to large of a
unit hurting throttle response.


.
 

canyoncarver

'hacking is learning'
Re: 78' KZ400B - another rabbit

Neat bike Monty, I love the stock hard bags on these.

Nebr, as always, thanks and keep it coming.

After putting a few beers into my wife last night, she took another look at the bike and somehow became interested. Even this morning after she woke up I had her look at it again just to be sure. Yep, looks like I should get it running ( as cheap as possible , ie, skipping all the head upgrades etc..) and let her ride it. I don't doubt it'll be a snoozer, she's used to her 2014 FZ6R but she seems to think the 400 is cute so I'll stick with it awhile.
 

doc_rot

Oh the usual... I bowl, I drive around...
DTT BOTM WINNER
Re: 78' KZ400B - another rabbit

is that a giant hole in the piston?
 
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