It sounds like your raditor cap is bad, not allowing the right pressure, which would cause the coolant to blow out, when the coolant get low, your motor's overheats.

Just a guess, but has happened to me.

I would recommend useing Evans Waterless coolant. evans

 

Also be sure to not hit the radiator with too high of preasure water, as it will bend the cooling fins. Take off the front rack, then the front cover and get a good look at the radiator, I thought I was getting mine clean until I looked at it this way.

SLG

 

Replacing the cap might be a good idea,

I've got a heelclicker on my 600, I rarely shift into low anymore, even running up on the trailer or going thru mudholes. I really didn't care for the high engagment rpm of the factory clutch setup. The heelclicker really does a great job for work and wallowing in mudholes.