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1970s KZ400. Which is the one to get? 27 Jan 2024 13:32 #894497

  • chopper1963
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Hi guys

I see KZ400s for sale now and again. Nearly always projects ... I feel that these bikes are some of the best looking that Kawasaki made in the 1970s. BUT I also remember when they were current a lot of oil leaks, carb problems and really bad vibration issues.

Question: Which is the one to get, ideally?

Question two: did they ever solve any of the issues with the 440 LTD and etc? And thusly will a 440 engine go in a 70s 400 chassis without becoming Dr Frankenstin?

Thanks for any suggestions

 

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1970s KZ400. Which is the one to get? 27 Jan 2024 13:48 #894498

  • Mcdroid
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www.kz400.com/ModelidentificationFrameset.html

I assume you are familiar with the above site...not sure how well curated the site is, but the site owner (now deceased) was the absolute guru of 400's and 440's.
Michael
Alvin, Texas

1982 GPz750
1977 KZ1000A
1978 KZ1000A
1982 GPz1100
1975 Z2A

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1970s KZ400. Which is the one to get? 27 Jan 2024 14:45 #894500

  • Nerdy
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I like the '78 and '79 400s from a styling perspective and because they have an additional hard oil line up to the head to reduce cam wear.

I don't know which issue(s) you're talking about with the LTDs.
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R

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1970s KZ400. Which is the one to get? 27 Jan 2024 15:15 #894502

  • chopper1963
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I was still very much gopher in the shop when these were around but I recall issues with the early ones. To my knowledge there were no issues with the 440s.

 

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1970s KZ400. Which is the one to get? 27 Jan 2024 16:52 #894504

  • Nebr_Rex
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Hi guys

I see KZ400s for sale now and again. Nearly always projects ... I feel that these bikes are some of the best looking that Kawasaki made in the 1970s. BUT I also remember when they were current a lot of oil leaks, carb problems and really bad vibration issues.

Question: Which is the one to get, ideally?

Question two: did they ever solve any of the issues with the 440 LTD and etc? And thusly will a 440 engine go in a 70s 400 chassis without becoming Dr Frankenstin?

Thanks for any suggestions

.

   When they redesigned the engine in '78 the oil leak problem was eliminated.
The oil leak problem can be fixed. The early engine used an exhaust cross over in the engine instead of just in front of the mufflers.
The hot sooty exhaust would heat up this part of the engine a little more and separate the head gasket from the  jug and head.
Think of water freezing and thawing in a rock formation or a paved roadway, same principle.
The cross over port is at the head gasket, one half in the head and the other in the cylinder jug.
To fix this the hole in each exhaust port needs to be tapped for a pipe plug. Installing these pipe plugs will seal off this cross over.
A couple of small holes will need to be drilled in the jug to relieve air pressure in the blocked off cross over.

A 440 into a KZ400 swap is bolt in except for, 1) the top mount on top of the cam cover, 2) charging system, carb spacing.


.
 
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


.
The following user(s) said Thank You: chopper1963, Wookie58, LuisLAN

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Last edit: by Nebr_Rex.

1970s KZ400. Which is the one to get? 28 Jan 2024 09:36 #894528

  • martin_csr
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Beware the KZ400.com forums as they may harm your computer. This was from several years ago. I don't know if the forums are now safe.

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1970s KZ400. Which is the one to get? 31 Mar 2024 14:28 #897110

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Deleted. 

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1970s KZ400. Which is the one to get? 01 Apr 2024 12:13 #897143

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   When they redesigned the engine in '78 the oil leak problem was eliminated.
The oil leak problem can be fixed. The early engine used an exhaust cross over in the engine instead of just in front of the mufflers.
The hot sooty exhaust would heat up this part of the engine a little more and separate the head gasket from the  jug and head.
Think of water freezing and thawing in a rock formation or a paved roadway, same principle.
The cross over port is at the head gasket, one half in the head and the other in the cylinder jug.
To fix this the hole in each exhaust port needs to be tapped for a pipe plug. Installing these pipe plugs will seal off this cross over.
A couple of small holes will need to be drilled in the jug to relieve air pressure in the blocked off cross over.


 
Is there an existing "how to" for this mod. I've been working on a 76 - 400s and took it on a 40+ miles for the first time. It worked great except for 2 issues; the first one is that there is a crack on the right engine case that is throwing oil all over the place, the second is the valve head gasket is leaking also. 
I wonder if it's worth it to replace only the gasket or if I should try to remedy the underlying issue?

This is a repost of my previous entry (Now deleted). I failed to included the quote I was trying to reference.

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1970s KZ400. Which is the one to get? 02 Apr 2024 08:40 #897159

  • Nebr_Rex
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" a job worth doing is worth doing right" 

Could you post some pics of your oil leak?
I'll get some to reference what what the problem is and how to fix it.

.
.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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1970s KZ400. Which is the one to get? 02 Apr 2024 11:15 #897171

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" a job worth doing is worth doing right" Could you post some pics of your oil leak?I'll get some to reference what what the problem is and how to fix it. 
Thanks for taking the time to help with this.
Please see the attached picture, I hope it helps.
I have a video that shows "bubbling" but I can't upload it because of the format

 
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1970s KZ400. Which is the one to get? 02 Apr 2024 12:31 #897176

  • Michi
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It looks an awful lot like someone sold you a pig. The photo appears to show that whatever gasket or sealant is there on the valve cover has been sprayed over, along with all the bolts as well.

You should remove the valve cover and take a look, and replace your cracked engine case. I think you may uncover many other faults as well.

On the plus side, these bikes are interesting. They will always give you some new and interesting issue to address every other week.
KZ440A LTD (1980)

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1970s KZ400. Which is the one to get? 02 Apr 2024 17:48 #897188

  • Nebr_Rex
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This is where the head gasket is. Almost all of them leaked there. The factory had a fix for it back in the day. 


.
2002 ZRX1200R
81 GPz1100
79 KZ1000st daily ride
79 KZ1000mk2 prodject
78 KZ650sr
78 KZ650b
81 KZ750e
80 KZ750ltd
77 KZ400/440 cafe project
76 KZ400/440 Fuel Injected

www.dotheton.com/forum/index.php?topic=39120.0


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