Try leaving the top clamp loose and push the spring past the clamp area and then pull the lower end down to the water pump. I tried the NAPA hose on my 1200, but didn't like the way it fit. Maybe I cut it wrong but it was a little off on the angle and seemed a little stretched, like maybe the was not enough length. I went and got the correct GL parts and never looked back.
I've had the same experience with the NAPA hose. It's on there okay but I'd have paid a few bucks more for the better OEM fit.