To jump or not to jump?
At this point, one should recognize the risk in using another vehicle to jump start a dead battery. If the bike has a shunt type regulator versus a series type, there will be issues but let's look at the rectifier first.
If one connects a battery in correct potential to the rectifier, the diodes "block" current flow so its just like trying to pass water through a check valve or closed valve = no flow. If one reverses the polarity, the circuit is virtually wide open with the only opposition being the series resistance of the wiring and components. Connect a 12 volt battery across a one volt buck circuit (one volt drop) and there will be 11 volts to create current flow. Since the remainder of the wiring and components have very low resistance it will be almost like hooking the jumper cables directly together excepting that the little regulator circuits will be in the way. The rectifier diodes will be cooked to a crisp in nothing flat. Unless you are lucky, the ignition module may suffer the same fate, depending on how it is constructed and whether the key is off.
If one connects in the correct potential, to a fully charged "12 volt" battery, no problem because the diodes will block flow and the starter + other components will be powered correctly. If the other battery is larger than the bike one and the jumper cables have low resistance, the engine may crank faster than usual but that's actually a benefit.
The risk is if the other vehicle's charging system is in operation. If the other vehicle's charging system is operating and has a set point higher than that of the bike's regulator then the bike's regulator will seek to lower the voltage by intervening in the circuit.
If the bike's regulator is a series type, it will attempt to reduce voltage by opening the circuits between the stator and the rectifier which will have no effect at all. The bike will (likely) start and the bike's stator will remain disconnected until such time as the voltage drops, usually because a jumper is disconnected. At this point the bike's voltage drops and the stator is reconnected, all continues as normal.
If the bike's regulator is a shunt type, the regulator will also attempt to reduce voltage but this will be by shunting (shorting) the positive and negative. The bike's regulator has a large enough shunt circuit to load the full capacity of the bike's stator output + a safety margin but not large enough to shunt the output of a lot more current.
So, what do we have? I shunt circuit which is designed to perhaps shunt 25 amps. It is connected to a typical automobile which has a..100 amp alternator...much, much bigger. So, the car is operating nicely, its regulator is maintaining its voltage at its intended set point which we will assume is 14.8 volts for the example. Let's say that the KLR's regulator's set point at this temperature is 14.6 volts which is not a big difference.
OK, hook up the cables. The car sees a small increase in load, the regulator says, "Voltage dropped I need to turn up the alternator output to hold 14.8 volts."
The KLR regulator sees 14.8 volts so it shunts current in order to pull the voltage down to 14.6 volts. Car reg. sees this and turns up its alternator. This goes back and forth for about the width of a . and "poof" goes the KLR regulator. Sometimes the car's set point is equal to or lower than the bike's VRR so no problem but as Dirty Harry said, "Do you feel lucky, Punk?"
So that's an over view of the charging system. Hope it is useful to someone?