Need help with coolant issues

[mncruiser]

For a while now I have noticed a coolant smell but can never find any evidence of leakage. I pulled the side cover and the overflow tank was completely empty and refilled it. Some times after a ride you could hear what sounded like a boiling noise and I suspected it was coming from the overflow but it quickly stopped so I didn't worry about it. About 2 weeks later I am still smelling the coolant and was given advice to pull the tank and look at all the hoses under there. Today I did just that but found nothing. I tightened all the hoses but none were really loose. While tank was off, I changed out the coolant and again the overflow tank was bone dry. Today I took the bike out for a ride and again smelled coolant. Back to the garage and pulled the side cover and it was empty again! Refilled and started bike up and of course, the level in the tank began to rise and eventually overflowed a little so I siphoned some back out. (Getting long, sorry) Fire the bike up again and coolant returns but doesn't overflow, fan runs so I shut it down after it cycled and the coolant tank goes nuts, it begins to boil (See link below for a short video on this)violently. I now know this is what I've been hearing. After the boiling settles down, all the coolant is sucked dry from the overflow tank.

What is going on? I was going to run it over to the dealer but he is the only KAW dealer near me and he knows it. not a fun place to visit!
Boiling video http://picasaweb.google.com/Onmylast...93198103132402