I want to build a custom bike around a KZ1300 engine. It’s a water-cooled inline 6. I don’t want the radiator to obstruct the view of that awesome engine.
Can I get, say, a 4-core radiator made that is smaller in height and width? What about “hiding” it in a chin spoiler like on some Top Fuel bikes?
As long as you keep the surface area for heat dissipation the same or more - it should be fine. You increase the fin density or fin length or go for integral fins to improve heat efficiency. But really, you should look at the heat load, then look at the rating for the radiator and go from there.
Plenty of water cooled machines utilise smaller radiators than you’d expect given the power rating of modern engines, this is so they can wrap a smaller race fairing around them.
To compensate for this there are two main approaches, use fans that are operated by a thermostat, and creative use of fairing airflows.
Benelli has an interesting way of doing things.
The radiators are situated in a duct that passes under the seat, and at the end of said duct are two fans, and this allows the aerodynamics around the front fender and main fairing to be improved.
All I’m saying is that you could try siting your radiators somewhere else and maybe use some sort of air scoop for when the bike is in motion and fans for when it is not.
Those scoops would also give you an opportunity to use your creative talents, turn them into dragons heads perhaps ?