My KZ750 nearly got me killed today. Need Older Guru Help

So had a look at the bike.
Tank vent is clean. lifted the paper filter and its totally cleaned and unblocked.
Started the bike, let it warm up. Sprayed Carb Cleaner on the carb boots. No air leaks there. Then THIS happened:

I put the multimeter on the battery and its charged at 14.77 at 2k rpm (its lithium). However I did notice that, while idling, the voltage would go from 14.77 very quickly to 13v and come back up. Then, after a while of idling it would drop down to 9v for just 1 sec and come back up.
The bike would for a LONG time without dips in voltage, but the dips did come back slowly.
Ive been told that the voltage regulator is the issue that cause the surging and bucking and shut off of the bike the other day - not shut off, but it would stop running though all the lights were on. Sounds like the voltage regulator.  Do you agree?

wrote:

So had a look at the bike.
Tank vent is clean. lifted the paper filter and its totally cleaned and unblocked.
Started the bike, let it warm up. Sprayed Carb Cleaner on the carb boots. No air leaks there. Then THIS happened:

I put the multimeter on the battery and its charged at 14.77 at 2k rpm (its lithium). However I did notice that, while idling, the voltage would go from 14.77 very quickly to 13v and come back up. Then, after a while of idling it would drop down to 9v for just 1 sec and come back up.
The bike would for a LONG time without dips in voltage, but the dips did come back slowly.
Ive been told that the voltage regulator is the issue that cause the surging and bucking and shut off of the bike the other day - not shut off, but it would stop running though all the lights were on. Sounds like the voltage regulator.  Do you agree?
 

Was your battery flat when you got home? If the answer is 'no' then I doubt the issues you are describing are caused by the voltage regulator. If the battery is still charged when you got home, the battery was still charging. And if the charging system is intermittent (which is possible), the voltage can fluctuate, but it could only fluctuate between the battery voltage and the charging voltage (this could potentially be the 14.88 => 13V you measured). And the bike should still run perfectly at the battery voltage - it needs to, if it didn't the bike wouldn't start. You may notice a small dip in light output from 14.77 to 13V.

If the battery really does drop down to 9V intermittently, that's a problem with the battery, or a very large short somewhere. Even with the charging system completely disconnected the a good battery will not drop below 12V unless you're putting a huge load on it (like when starting the bike). You would also see your lights dimming significantly any time the voltage dropped that low.

I'd check that your battery is tightly connected (including both sides of the grounding strap), and that the regulator/rectifier connections are clean and tight. Measuring as low as 9V is more indicative of a failing battery, a loose terminal, or a short in the system than a failing regulator. A short could give the symptoms you're experiencing - if the charging system is shorted the voltage will drop low and the power to the coils would be significantly reduced.