Kawasaki and Triumph are way out there on heavy-weights.
...gene
Yep, my old 2005 Vulcan 2000 was 125ci's of pure meanness. It was also a good looking engine at that, complete with the dual external push rods that are so Harley'esque in appearance, unlike Yammie's single tube version. There's no reason why Harley can't produce a much larger displacement engine with liquid cooling.
I'd love to have that much motor/power on my Roadie.
That said, I won't buy the first year liquid cooled Harley. Learned my lesson with the '07 SG. Same reason I don't run out and install the latest/greatest OS on my PC's. I'll wait a year and let the bugs get worked out in the public "beta testing".