TOPIC:

Interesting to know it is a safety feature to prevent a fire in the event of an accident, leads me to wonder on how wise it was to remove, and as to why Kawasaki never resolved if they where failing causing people to remove them.

I think it's less about fire prevention and more about this exact problem here- hydrolock, due to the fuel filling the cylinder and being unable to compress, due to being a liquid. Each of the "Big 4" (Honda, Yamaha, Kawasaki, Suzuki) had their own solution to the problem. The Yamaha XS1100, for example, used vacuum petcocks, like the one the OP added to his KZ. In fact, the Special models of the XS11 had a system so complicated, it's generally known as "the octopus". It's also generally pitched, because it has a rather high rate of failure.

The KZ1300 solution was the aforementioned solenoid. Again, normally pitched due to failure. Not sure what Honda did, but on my Goldwings of the period, they didn't even bother- both my GL1000 and GL1200 have simple manual petcocks.

In theory, the float valves in the carbs should prevent any extra fuel to enter the engine anyway. But the simplest, easiest way to bypass ALL of this and not worry about it at all is to just fit a manual petcock and remember to turn it off.

Reality is Leaking carbs, hydraulic lock are all secondary problems, Fuel can only get to the carbs via the tap. If shut off, whether vacuum or Manual and its still draining down the tap must be faulty. All mine are fitted with manual petrol taps and only ever had a problem if I have forgotten to shut the tap off (have had one of these for 17 years) I think it's worth re-fitting the solenoid valve to see how it goes, if it works then you have a result as well as peace of mind. A spare bit of hose and a couple of jubilees under your seat will get you out of trouble if you need to by-pass.

Not to be a prick or "know-it-all," but the fuel solenoid (fuel valve) in Kawasaki terminology was designed and installed only as a safety device to prevent fire in case of an accident. Hydrolock and fuel contamination of the oil sump were never considered. The same system of initiating fuel flow cut off was used on Japanese cars of the same vintage. The only difference was the voltage to the fuel pump relay was turned off as opposed to the voltage to the fuel valve turned off.

The fuel valve is opened only in two situations:
1. During starting when the start button is pressed.
2. When the engine is running.

The "complicated relationship with the safety switch in the clutch lever" (starter lockout switch) is not that complicated. During starting, current flows from the ignition switch to the engine stop switch. From the engine stop switch, current flows to the starter lockout switch. From the starter lockout switch, current flows to the starter button. Pressing the starter button sends current to the fuel valve and to the starter solenoid. It is as simple as the starter button energizing the fuel valve during starting. Both the engine stop switch and the starter lockout switch must be "on" before the starter button can send current to the fuel valve.

After the engine starts, AC from the alternator goes directly to the fuel valve and keeps it open. In the case of an accident in which the engine stops running, there is no current from the alternator and the fuel valve closes.

The fuel valve solenoid coil, like all coils, cannot run continuously on DC or it will burn up. Continuous operation "on" requires pulsating DC or AC. That's why the solenoid operates on AC with the engine running.

Really like that answer, answers some of my thoughts and probably a lot of other peoples. So if these were failing it was not necessarily the Valve, if it opens and shuts as and when it is supposed to with no intermittent faults all should be good. Cheers Globemaster

Thanks Mark. I really liked your succinct analysis that reality is leaking carbs. That is it in a nutshell. As you pointed out, there is no "carb leakage" if the petcock actually turns off the fuel flow.

I don't know what the "failure" of the fuel valve constituted. There were many reports of the valve failing in the closed position and completely shutting off fuel flow. Unfortunately, I've never had a "failed" fuel valve that I could autopsy. My guess is that either rust particles from the fuel tank caused the valve to seize closed, or insufficient output from the alternator would not allow the valve to open.