1975KZ400D, head gasket leak, any top tips?

Hi all, as title suggests head gaskets is leaking on my kz400d. There is a lot of oil coming out of the head gasket area. I am fine with replacing the gasket but my question is before I start does any one have any tips that would help to ensure success at solving the problem? Eg use of sealant vs no sealant, best gasket to use etc. The engine was rebuilt by PO recently so they obviously didn’t get it right, which makes me think it might not be straightforward.

Many thanks

 

If you have a head gasket with a sticky surface (OEM) don't use any sealant. If not, you can apply a very thin coat of head cover sealant to the outer 1/8" of the head gasket, keeping sealant away from the metal compression rings.
Also, measure the thickness of the oil passage o-ring. Make sure it is thicker than the combined thickness of the head gasket and the depth of the o-ring pocket in the head.

Thanks. So I’ve taken it apart and there are no o’rings fitted at all.

There doesn’t seem to be any pocket for them either. Do they just sit inside the gasket?

ta

Partzilla shows an o-ring. Part #2. 

Ok thanks, I’ve ordered some o’rings so that should sort it hopefully.
 

See page 36 in the factory service manual.

www.kzrider.com/filebase-alias?task=down...id=1231&catid=11&m=0

As long as you have it apart, you should also replace all of the gaskets and orings for the cylinder head cover.

Will do, thanks.

anyone know if the eBay gasket kits any good?

Like this one ebay.us/m/rSwIiw

I haven't had any luck with those kits on my KZ305. 
From my recent post:Re: Are my head studs stretching? KZ305 Today 21:49
#914124
This is the 3rd time in the past 5 years, that I replaced the head gasket do to oil leaking. However, this time I was able to source a NOS OEM head gasket. The first two times, I used gaskets from after market gasket kits. Time will tell.
 

Ah yes that’s what I wanted to avoid, I’ll see if I can get NOS, the early ones seem very rare in the uk though.
 

Just taken the cylinder base off, there are no o’rings  there either! Just lots of silicone everywhere, seems to have been some bodging going on.
Once I sort all the missing bits, what’s the recommendation on base gasket, Hondabond or similar, sealant or nothing?
Ta.

Read my post here.


.Re: 1970s KZ400. Which is the one to get? 27 Jan 2024 16:52 -  27 Jan 2024 17:26
#894504

chopper1963 wrote: 
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.