TOPIC:

So I decided to go for a ride today, took the gpz to get a better feel for it, since I just got it.
The PO said it needed a valve adjustment soon, but should be fine and I've been riding it for errands w/o any real issues.

Well today it crapped out on me.
Lost power slowly, then shut off.
After a few more cranks it started back up and I tried to get home... Seemed fine, revved to 5k smooth, easy and readily.
Then it shut off again.

So now I've got a guy from our local community garage on the way to pick me and the bike up.
But my question is this...
Is it likely this is related to the valve adjustment needing to be done sooner than later?
Is it possible it's jumped timing? A buddy said he thought he heard the timing chain slapping, I didn't, but this bikes kinda loud anyways.
Is this an interference or no interference motor?

As in if it jumped timing what are the odds all the valves are bent to hell?

clean your tank, clean the peatcock, clean the carbs, change fuel tubes, check float levels and do in that order.
The cam's don't jump the chain, but it will be a good idea to check them after cleaning the fuel system and then at last sync the carbs.
Make sure to remove the cam chain tensioner before fitting the cam cover and while at it, look the tensioner over and give it a good clean and grease up before fitting back.
The Workshop manual could be found under Articles.

Happy wrenching!

/A

You have raised several issues in your post which I can try to lend some suggestions to help calm your fears and give you some insight.

Valve adjustments a very very important and left unchecked can cause long term damage over time. Using a malfunctioning factory cam chain tensioner can lead to a sloppy cam chain that rattles like crazy. But the tensioner would have to almost completely fall apart for the cam chain to slip a tooth. You will absolutely need to verify that the cams are in the correct index when BEFORE you go to adjust the valves. That being said, here are my thoughts on what brings you here today.....

Scenario A:
The symptoms you describe sound like either one of your coils may be bad. They have a tendency to run fine until they begin to heat up and thats when they suddenly "stop working". But once the defective coil cools down, it will begin to function properly until the point it overheats and fails again. (This used to happen to me when I drove air-cooled VW's so much that I never left home without a spare coil.) Each coil powers two separate cylinders and while the engine will idle and "kinda run" on three cylinder, it will not run at all on just two. Pulling spark plug wires and testing with a spare spark plug will show if you have a loss of spark when the engine fails to run/start.

Scenario B:
It can be something as simple as your gas cap breather is not functioning properly thus creating a vacuum in the tank. The carbs are gravity fed by the tank and cannot flow against the slightest vacuum caused by a clogged breather. So your carburator's may be starving for fuel until the engine stops and the vacuum in the tank is slowly equalized and then fuel will begin flowing in the carbs letting the motor start agin. I have had this happen once and diagnosed it by running with the gas cap popped open and noting that the engine never died when open.

Scenario C:
The carbs are clogging and/or in desperate need of a rebuild with new rubber components. The running fine then dying sounds like a float valve that is sticking leading flooding the carb or running the carb out of fuel. I have had sticking float valves cause this symptom as well as carbs passages so full of rust (from a rusted tank) clog passages so that the fuel could not be suppled fast enough leading to stalling. Regardless, you will NEED to remove the carbs to properly access their condition and more than likely replace EVERTHING that is rubber or that is a gasket. Jets can be cleaned and do not need to be replaced unless they are physically damaged. (Always replace the float valves as they may look good, but even if the rubber tip looks good, the tension mechanism built into the body of the valve can be frozen or sloppy leading to flooding or slow fueling.



I'm sure they other members will also have good suggestions and insight, so you will have lots of guidance.
Keep us updated!

The valves tighten with mileage. Wait too long and the valves won't close anymore and when you get to that point the valves and head can become damaged. Stalling when hot is a classic symptom. Personally, I never put on old bike purchase on the road without checking and adjusting the valves first.

So I managed to get into it Saturday.
Replaced the chain tensioner and did the valve adjustment, several of the valves are as adjusted as my shim kit will go, down to 1.85 and still making zero cam clearance.
So it looks like I need to have the seats redone and valves replaced.
It would seem that I am rather out of my depth on this bike.

Bummer. Sounds like someone either neglected maintenance and damage occured or a valve job was done and the machine shop didn't tip the valves to put the installed height to the proper window. Table H21 in the factory Kawasaki service manual details the proper valve height. It's customary to tip the valve stem to control height after cutting the seats and/or wear in the engine.

I'm between getting out from underneath this as I;m out of my depth, and getting the head fixed.

What does this repair run on average? I poked around a few places and couldnt even find the valves available.

Valves are available@

www.cmsnl.com/kawasaki-kz750r1-gpz-1982-...st/8650.html#results



but new valve will not cure the bad valve job done to the valve seat rings, (seats rings are cut to deep and need to be renewed).
better buy a cheap used cylinder head from evil-bay.

Advise against grinding valve stem tips as these are hard finished in stellite.
One option is using the GPz750 camshaft which has a smaller base circle in some of the 82-83 models

HUH? LOL "tipping" is commonly done. If that won't work larger valves are called for.
Steve

The kawasaki service manuals specifically advise against it, as the valve end is hardened.
I would guess that unless the ground surface is heat treated again, there would be rapid mushrooming of the valve tip.

weeZee wrote: The kawasaki service manuals specifically advise against it, as the valve end is hardened.
I would guess that unless the ground surface is heat treated again, there would be rapid mushrooming of the valve tip.

As Steve states, it's common procedure to grind the valve end to gain clearance. There is a warning in the service manual for my 750 about this but the reason being there could be issues, if the valve is cut too much, where the valve keepers would stick up above the end of the valve and that will cause problems. There is no reference to a hard coating on the valve in the manual. Further, Jay, owner of APE Racing, has posted here on this subject before and they tip the valves regularly. They even go so far as to cut down the valve keepers so they don't stick up above the valve in more extreme cases. Apparently they service a good many KZ Police bike heads and this is what they do to keep them on the road.