KZ440 - Can't get it running right.

Hello,
A friend of mine recently got an 1982 KZ440. Here's whats happening:

1. It seems to only want to fire up and run on prime. If we switch it to on when its idling and give it gas it dies.
2. The spark plugs turn black almost instantly
3. Sometimes it won't reach past 5kRPMs - other times it will reach about 8
4. Can only reach 40mphish WOT.

Here's what we've done so far to try to correct the issue:

1. Removed and cleaned the carbs. Even tried a different set from a parts bike(condition unkown). Similair symptoms
2. Adjusted the valves(which were horribly off)
3. New plugs
4. Ajusted the throttle and idle

The bike started out only able to go 10MPH so doing what I mentioned above got us another 30. But what else can be going wrong here. Could it just be that it needs a set of new/rebuilt carbs? Or something else?

Would assure ignition timing is advancing as it's supposed to when increasing throttle.

Good Fortune!

EvanKZ wrote: Hello,
A friend of mine recently got an 1982 KZ440. Here's whats happening:

1. It seems to only want to fire up and run on prime. If we switch it to on when its idling and give it gas it dies.
This indicates that the petcock is malfunctioning, probably full of crud. It should be taken apart, carefully cleaned, and all the rubber bits replaced. This also suggests that the tank has crud in it and may mean that the newly cleaned carbs have new crud in them unless a new fuel filter was installed first.


2. The spark plugs turn black almost instantly
Several possibilities--
-Seriously rich mixture caused by improperly set fuel height, failing float valves (see crud comments above) or maybe badly jacked up jetting. Are the stock intake and exhaust systems in place? Condition of the intake manifolds and air box boots?
-Dried out and leaking valve seals that allow oil into the intake ports.
-Very weak spark due to failing ignition components.
-Bad or stuck oil rings. Has the bike been sitting for years unridden? Compression or leak down test?
-A combination of some or all the above.


3. Sometimes it won't reach past 5kRPMs - other times it will reach about 8
See Patton's comments.


4. Can only reach 40mphish WOT.

See Patton again.

Here's what we've done so far to try to correct the issue:

1. Removed and cleaned the carbs. Even tried a different set from a parts bike(condition unkown). Similair symptoms
Absolutely sure that all the tiny pilot jet passageways were absolutely clean and that there are no problems with torn diaphragms (CV carbs only) or re-contamination for the fuel tank?


2. Adjusted the valves(which were horribly off)
Good. A common problem.


3. New plugs
Also good.


4. Ajusted the throttle and idle

Probably not real important until the other problems have been ruled out or repaired.

The bike started out only able to go 10MPH so doing what I mentioned above got us another 30. But what else can be going wrong here. Could it just be that it needs a set of new/rebuilt carbs? Or something else?

A genuine Kawasaki factory service manual will be invaluable in this process, as will the proper tools.

Pic of the bike will help.
Steve

Patton wrote: Would assure ignition timing is advancing as it's supposed to when increasing throttle.

Good Fortune!

Thanks, I'll have to check this out. I'll let you know how it goes!

And Steve, a picture of the whole bike is all I have at the moment, I'll attach it.

The problem that people often run into is they do things backwards. Instead of performing maintenance they perform troubleshooting while a baseline has never been established.

BTW, testing the petcock would be a good place to start. And make sure fuel is not backflowing down the vacuum line. Next clean the carbs properly.

It does sound like you may have more than one problem,

Keep in mind, bikes can run for a little while on the gas in the carb bowl, so if it starts on prime, and runs, but then dies on 'run', it could just be that it runs on prime, then isn't getting any gas on 'run' and just goes until you drain the carb bowl. I agree with prior comment about going through the petcock. There are relatively inexpensive rebuild kits available that would allow you to replace all of the internal parts (probably unnecessary, doesn't really hurt). Also maybe check/replace the vacuum line from the carbs to the petcock.

The 'different carbs same problem' and quick transition to black plugs has me wondering if you've got oil getting into your cylinder. Have you done compression test?
You mentioned that the valves were horribly off. If the valve lash is too tight, this can damage the valve seats (requires pulling the head to lap the valves, or taking them to an engine to be ground in more severe cases). With proper valve lash, you should hear some valve noise at lower RPMs (somewhat common complaint about these bikes).

On the 40 MPH bit, a 440 isn't a particularly powerful bike. If you're running in too high of a gear, the bike can have trouble accelerating at speed. If running at 40 MPH and can't accelerate, down shift until you're north of 6K RPM. A good running bike may be able to power through a heavy rider at lower RPMs, but right now sounds like the bike is a little rough.