written by Dr. Dave (tdah73 on the forums)
1. Here's the filler cap. You'll need to remove the right side air intake duct cover and pull back the duct itself. Make absolutely certain you have a cool engine. Opening this cap while the radiator is still hot WILL result in some painful steam burns!
2. Locate the coolant drain bolts. Pictured below is the right side cylinder drain bolt.
3. This is the left side cylinder drain bolt below.
4. On the left side of the bike, just above the oil drain bolt, you'll find the 3rd and final drain bolt (water pump drain bolt):
5. Let the old coolant all drain out it with the 3 bolts off into a suitable container. NOTE: Coolant is lethal to animals. It's rather sweet smell and taste can attract them so you want to make sure you don't leave any on the ground. If you spill any, make sure to hose it off well.
NOTE: If any of your hoses look bad, worn, dry or have any cracks in them, now is the time to replace them.
6. Flush the system
with water. It's not necessary to use distilled water for this. Just put a hose
at the filler cap and let it run through for a minute or 2 with the drain bolts
off, again use a large container to contain what comes out. Replace the drain
bolts, and fill with fresh properly mixed coolant with a ratio of 50% water
to 50% coolant. Total capacity is 1.95 liters (2.06 qts). Fill the radiator
to the neck (the part where it gets narrow where you're pouring in the coolant).
I found that if I shook the bike a few times, it'd help the coolant to work
its way into areas that had air pockets. Replace the cap, and fill the reservoir
to the high fill mark. Start the bike, let it run for a few mins, and recheck
the level while checking for leaks.