Top end rebuild 78 kz1000

After a great year of riding I knew it was time to redo the top end, I finally got around to checking compression on the 77 replacement engine that I ran this year and found all 4 cylinders at 60 + - :whistle: Note; she still ran pretty good with low compression, just lacked power on takeoff, that explains where the oil was going.

The 78 head is going to Larry C as soon as I can find a good box to send it in.

The cam chain rubber wheels are shot and will have to be replaced but I cleaned up the bottom end last Winter and replaced all the seals and O rings ,
It is holding up great ( no leaks) so I want to leave it in the bike and just swap out top ends, if I can.

My questions are; if you replace the cam chain gears should you replace the cam chain at the same time? it has somewhere around 60,000 miles on it , and if so is there good replacement chain with a master link or do I need to split the cases again :pinch:

Also I am "not" looking to make this engine more powerful, just to make it run as good as new,
I have heard that the cylinder walls can be honed and special rings can be used to give new life to the stock pistons, or am I better off going with a 1075 kit?

The bike is plenty fast for me when it runs right and I don't beat it like a red headed stepchild anymore,
my apologizes to any red headed stepchildren whom may take offense to that last comment.

I still do enjoy a spirited ride from time to time and don't want to take any chances on having a problem so I will do what ever I have to do to keep her reliable .

Thanks,

JD

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bluej58 wrote: My questions are; if you replace the cam chain gears should you replace the cam chain at the same time? it has somewhere around 60,000 miles on it , and if so is there good replacement chain with a master link or do I need to split the cases again :pinch:

I know you can buy a cam chain with a master (you have to buy th , I opted for buying a chain riveting tool to press out old rivets and press in new ones so you don't have to split cases if you have the right tool.
eBay link to tool,

As for the rings, I believe there are over sized rings. I would suggest checking your FSM to find the service limits on the cylinder before ordering parts. You may be able to get away with honing and a new set of rings. You can rent a cylinder hone from Auto Zone for just a deposit. If you have never honed cylinders let me know. I'm about to redo mine and can try to do a video.

With 60k on the clock you are sure to have some wear at this point now. Personally, I'd rather have OEM oversize pistons vs. an aftermarket big bore kit but that's just me. A Wiseco big bore kit is cheaper.

I have not cracked open the top end of the 77 engine that is in the bike now, just in case we get a decent day to ride , but I will measure the cam chain that is in the 78 engine and if it is within allowed limits I will probably stick with the original chain that is in the 77 now because it only has around 30,000 + miles at this point.
That way all the steel gears will still match up and I can just replace the rubber wheels and dampeners .

I am planning on using the head, jugs and piston off the 78 so I will need to make sure that the 78 piston pins and the connecting rods from the 77 are compatible, (with in tolerance )

JD

A great source for shipping boxes is GRANGER. The have hundreds of sizes.

Please replace the cam chain. With 60,000 on it, its job is done. Since Kaws are a interference engine, if it breaks so does everything else.

Try to get a quality vintage NOS cam chain. Some of the new stock is crap.

The chain I want to use is wrapped around the crank in my 77 engine with only 30,000+ miles on it and that is the rebuilt bottom end that I am using.
I would rather put a new cam chain in but I am thinking that the old gear sprocket on the crankshaft and will wear it out quickly like on a drive chain if you don't change the sprockets :huh:
All the sprockets are easy to get to and change at this point but how do you change the one on the crank?



I will report my findings
JD

You don't. That sprocket will out last you. Change the chain. I used Liska cam gears and they are half the cost of OEM plus they won't come apart. They make a whurring noise like a turbine kinda. I like it. At this point you might consider oversize 1015 10.25/1 pistons if yours are out of spec. If not, re use your pistons with new rings. Check your clearances at top, middle and bottom. If all good, put together and ride the piss out of it.
Steve

My personal opinion only.......only use a camchain with no master link, why risk it separating? And I would use a Heavy Duty one at that, only a few bucks more. Yes, you have to split the cases but I don't think that is such a big deal. You have done that already so you get to check your own work and see if anything has worn out. There is no way to change the sprocket on the crank (short of having someone take the crank apart) I don't think the crank sprocket follows the same rules as the chain drive regarding uneven wear when replacing only the chain so you should be fine keeping the original crank.

Well we measured the jugs and the pistons and they are looking real good, well inside service limits.
I have started measuring the new rings end gaps and they are also looking good, .014 + -

We weighed the pistons and they are;
# 1 - 211.1 grams #2- 211.0 grams #3- 214.3 grams #4- 210.9 grams

1, 2 and 4 pistons are very close to each other but the number 3 piston is over 3 grams heavier :blink:
What can I do?

Did you weigh the pistons with their respective pins?

Good point, no :blush:
Now I have to wait until Monday to weigh them.
Thanks for the tip BB

60,000 miles and you plan to keep bike ? split the cases and do it right you are well on your way to worn parts I can bet the clutch hub is loose, trans dogs worn, crank ? can chain history, cylinder studs will be weak, valve guides shot, valve seals gone, Valves ? , Valve springs shot you will be suprised what you find do it right and you should see 60,000 more miles out of her, When I was A Kawasaki Mechanic I had a customer bring in a 1974 Z1 900 with 100,000 on the clock she was using some oil and was a little down on power customer thought it would be a engine rering till i tore i down but he was happy to fix it the correct way said it [ bike ] didn't owe anymore we rebuilt it and away he went he just loved that bike he bought it new in 74 put a wind jammer on it and went every where on it.