KZ440 '83 - Top End or Complete Rebuild

Last couple of rides my '83 KZ440 has been a little weak, and I've noticed some intermittent valve noise (primarily at lower RPMs), so I ran a compression test, and it turns out that I'm down about 35 PSI below the readings I took last summer. OUCH!

My instincts tell me that a valve grind and new head/base gaskets would likely clear it up. I could spec the journals, cylinder/piston clearance and rings, etc. while I have it apart.

So, I have been doing some shopping, and keep finding that full engine gasket and O-ring sets aren't really any more expensive than top end gasket sets on their own. I do realize that if doing a full rebuild I would want to also replace bearings and oil seals. I've got a good local bearing shop, so that should be relatively painless.

I guess I'm looking for advice on 2 things:

1. Top end rebuild, or go through the whole engine?
2. Any strong recommendations for the Athena vs. Vesrah gasket kits?

Also, added question. If I do pull everything apart, what options are out there for restoring the surface finish on the engine case/covers that have dulled some over the years?

How much psi did you get and did you try some oil in the cylinders to seal up the rings?
Either brand of gaskets will work. As for the engine bearings only Kawasaki made them for your bike.
And what is your valve clearance?


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You may not have tested the compression properly. To do so :

The engine must be warmed up to normal operating temperature. The pistons taper in near the top so with the engine warmed up they expand near the top which helps the rings seal against the cylinder walls.

The battery needs to be fully charged.

The throttle needs to be held all the way open.

All spark plugs must be removed.

If you do all that and compression is still low you should perform a leak down test. That will identify where the compression is leaking (could be valves, rings, head gasket, etc.) If you remove the cylinder head before performing the leak down test you will have lost the opportunity to use that diagnostic tool.
Ed

Did all that, except the leak-down test.

For the other poster's question, PSI came in at 80 left, 90 right, The left was at about 140 previously, and the right was at 135 previously (the 35 PSI drop being an understatement, same tester, procedure used both dates). When I added oil to both cylinders, no significant change in PSI (there's always a little, as the oil displaces some of the head space). given the lack of difference there, truth be told, my inclination is to pop the head, leave the jug in place and not even bother with the piston skirt, bore, ring measurements, but I know people on this site call out everything you do 'wrong' so I wasn't going to mention that little bit of 'see if I'm OK without'.

While I understand the value of the leak down test, My measurements are out of spec and something needs fixed, so I don't really see the value of buying a leak down test kit when I need to pop the top, and for the price of a bottom end gasket, and minimal added effort, will have an opportunity to take a direct measurement.

I adjusted valve lash last fall and was in spec. Haven't taken a direct measurement this time around, but am inclined to believe that they don't wear that fast (also, wear may explain noise, but would not explain the reduced compression, as wear creates a space, not pressure).

EricTheLeg wrote: Did all that, except the leak-down test. ........

While I understand the value of the leak down test, My measurements are out of spec and something needs fixed, so I don't really see the value of buying a leak down test kit when I need to pop the top, and for the price of a bottom end gasket, and minimal added effort, will have an opportunity to take a direct measurement.

You don't need to BUY the leak down tool. Autozone and other car parts places have loaner programs in place that let you borrow tools. You put down a deposit (the price of the tool) and when you return the tool you get 100% of your money back. I have used these programs when I need a tool I new I would use only 1 time. You really should check it out, I was impressed at how easy and helpful these programs are. Ed

www.autozone.com/test-scan-and-specialty...wn&fromString=search

Athena gaskets are garbage and Vesrah are marginal. Get OEM Kawasaki gaskets if you value oil tightness and quality. Kawasaki doesn't sell a kit but it's easy enough to purchase the gaskets/seals separately. You can typically find great deals on OEM gaskets on ebay too so the price shouldn't be prohibitive.

EricTheLeg wrote: Did all that, except the leak-down test.

For the other poster's question, PSI came in at 80 left, 90 right, The left was at about 140 previously, and the right was at 135 previously (the 35 PSI drop being an understatement, same tester, procedure used both dates). When I added oil to both cylinders, no significant change in PSI (there's always a little, as the oil displaces some of the head space). given the lack of difference there, truth be told, my inclination is to pop the head, leave the jug in place and not even bother with the piston skirt, bore, ring measurements, but I know people on this site call out everything you do 'wrong' so I wasn't going to mention that little bit of 'see if I'm OK without'.

While I understand the value of the leak down test, My measurements are out of spec and something needs fixed, so I don't really see the value of buying a leak down test kit when I need to pop the top, and for the price of a bottom end gasket, and minimal added effort, will have an opportunity to take a direct measurement.

I adjusted valve lash last fall and was in spec. Haven't taken a direct measurement this time around, but am inclined to believe that they don't wear that fast (also, wear may explain noise, but would not explain the reduced compression, as wear creates a space, not pressure).

You are on the right track. Unless there is some scoring on the cylinder wall I wouldn't pull the jugs either.
When you pull the rocker box check to see if anything is out of whack.


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Thank You Nebr_Rex and Nessism!
I'll pick up an OEM Kawasaki Head gasket and oil seals and pop the top.
Once I've got the top off, I'll decide if I'm pulling the jugs. Since that could mean another parts order (rings, and/or pistons, machining, etc), I'll hold off on the bottom end gasket for now.

At this point, I really don't see the gain in opening up the crank case (I've been through all of the gears, several times while riding, no signs of problems, also I'm not losing any oil that I've noticed, which I should have by now, I've been riding the bike for several years). There is really no incentive to open up the bottom anyway, since I'm buying OEM gaskets individually, rather than a set.

At this point, questions answered, I should be fine.


Nebr_Rex - on a side note, I lived in Nebraska when I originally picked up the bike. Awesome place to ride! Currently I'm in Western Washington. The mountains make for some great views and rides, but it takes a while to get free of civilization and traffic.

I use aftermarket gasket kits for the 440 that cost just under $40. Never had a problem with fitment, quality or durability.
And I have put a lot more stress on a 440 than probably anybody. www.dotheton.com/forum/index.php?topic=39120.0
All the seals can be acquired for around $20/$30. Only one seal is discontinued and that is for the clutch pushrod.

On your side note I used to be an over the road truck driver. Never been over Snoqualmie Pass [ or New York City/Long Island ]
but I've crossed Cabbage many times. I drove for a flatbed outfit which ment I delivered to some out of the places.
Your neck of the woods has some really nice roads. Even I5 in southern Oregon and Northern California can get twisty.


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I finally got some time. As noted earlier, I pulled the top end, lapped the valves, ran the pistons to bottom inspected what I could of the jugs from the top (looked great, as it should, bike only has about 8K miles on it),

With freshly lapped valves, compression back up in the 150 range.

I used the $40 gasket set, so NEBR_Rex, I may come looking for you if that doesn't work out (joking).

Bike still hates modern gas, but that's a carb problem, if there is a fix for it.
There was a bit of carbon in the cylinders, looks like oil was coming down the valve-stems, so hopefully new seals works for that. The exhaust valves were pretty gummy, and took a bit of lapping, so I think that's where I was losing my compression.