Drained radiator to change coolant. How do you refill radiator when reservoir only takes about 3/4 of a quart?

So what's the deal with this eh? We know we're driving liquid cooled bikes, we know the coolant should be replaced every year or two to prevent corrosion (and, coincidentally protect the system from extreme cold) but when was the last time you changed coolant? Well then it's about time right? Below are instructions straight from the Kawasaki Maintenance manual. One caution. A helper is always handy when removing the gas tank. One person to hold the tank, the other to remove hoses (especially in the case of the FI).
And what coolant should you use? Kawasaki recommends a permanent type antifreeze (a mix of soft water and ethylene glycol plus corrosion and rust in inhibitors) for aluminum engines and radiators (silicate free). If you're looking for other options check out this other Fixit page. For whatever it's worth I use Honda Pro Coolant. It is pre-mixed with de-ionized water and comes in a blue quart bottle. Cost will be around $4 a quart but you're going to know it's good for your bike.
Total amount needed for a complete refill is 2.3 liters or 2.43 quarts. You'll use most of the leftover half quart to refill your coolant overflow tank.
So lets get to it!

1. Place a container under the radiator drain bolt (bottom of radiator) and remove bolt. Careful, there is a rubber washer that can fall off the bolt. Lose that and your radiator will be drip, drip, dripping away until you find a replacement.
2. Remove fan controller unit (for cleaning) & reinstall. (dealers tend to skip this since it can be a little time consuming to get to)
3. Remove or pull back gas tank (Gadget note: removal is much simpler on the carbed bikes so you might as well get the tank out of your way. FI riders may want to remove the vent hose(s) from the rear of the tank then just move the tank rearward about three inches. This will give you access to the radiator cap)
4. Remove radiator cap
5. Remove water pump drain bolt (lower left corner) so any coolant remaining in engine can dribble out. It'll be less messy if you can fashion a funnel from something to guide the coolant to your drain container.
6. Remove right side cover and reserve tank bolts then reserve tank. Remove hose from container and drain coolant. Clean tank thoroughly and reinstall. (a bottle brush helps with this cleaning)
6a An optional step here. Using distilled water and white vinegar create a 50/50 mix. Put the drain plugs back in your radiator & water pump then pour the mixture into the radiator cap opening. Put the cap on and run engine until warm. Let cool and drain the mixture. Pour clear (distilled) water through the system allowing it to drain from the radiator and pump exits flushing all the vinegar/water mixture out.
7. Mix your coolant (unless you purchased pre-mix). Make sure all the drains you've loosened are tight. Pour coolant slowly into filler neck. Fill overflow tank to the 'full' mark.
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At this point there are two approved methods for re-filling the radiator. The first uses the air bleeder bolt which is forward of the radiator cap (looks like a brake bleeder). The other is probably the method you've used with your car, the 'engine running' method. Either way you're likely to spill some coolant so do this someplace where you can get a hose on the spill and rinse away easily.
Method 1, using the air bleeder bolt:

1. Install radiator cap
2. Fill reserve tank to the "full" level with coolant and put the cap on
3. Bleed air from the system using the air bleeder bolt in the casting below radiator cap. (torque on that bolt is 69 in lbs)

Method 2, running the engine and letting the air out through the cap opening:

1. Start engine (radiator cap off) and run until no more air bubbles can be seen. Tap radiator hoses to force any remaining air bubbles to the top. Stop engine, add coolant to top of filler neck. Install cap
2. Remove reserve tank cap again and fill tank to the 'full' level. reinstall cap.
3. Install side cover
Finally, Ride. Check the reservoir level after the engine has cooled to be sure the coolant level is proper. Top off to the 'full' mark if its low

Under the the gas tank