I picked up my wife's Vstar 650 on Saturday from the garage. Used te dealer's concrete ramp to load it up into my SCrew bed. Drove it home and unloaded it with ramps. No extra supports used. Had absolutely no problems.

And I believe the capacity is rated at 500#.

 

I recently moved an air tight woodstove. The stove was attached to fridge cart for easier moving around. Anyhow the stove ended up sitting on the tailgate for a few moments while my pal and I caught our breath. No damage to the tailgate. I dont know the weigth of the stove but the sucker was loaded with fire brick and the stove was made of 1/4 steel. It was a ball buster and I'm not moving the thing again.

 

I've toted my Bandit 1200 around in my S'Crew, and its definitely on the tailgate, no problems at all riding it up, and the gate doesnt even seem to move or flex.

You'll be fine.......