I believe that the heat transfer isn't as good with the oil (since it is MUCH thicker than your conventional coolant) as it is with coolant. It takes longer for the heat from the oil to be transferred to the atmosphere resulting in more heat in the engine

 

FWIW, I thought HD already had a liquid cooled bike now...the V-Rods.

 

It really wouldn't bother me all...although I'm plannin' on keepin' my Heritage for a loooooooooooong time anyways.

Before going w/HD bikes in '08, my last two previous non-HD bikes were both liquid cooled...a Honda Interceptor and a Kawi Z1000. Both were damn good bikes.

Just sayin'.

 

Have to say no thanks to water cooling. Like my air cooled, hot running, inefficient, old tech Harley.

 

The question, or answer depending on what side of the fence you are on should not be why not but rather why? A water cooled engine would cost more. The bike also would have to have the frame re-engineered, not just the motor to accommodate the radiator. The are butt ugly with the added pieces and big ugly radiator, it's something else to sevice or to go wrong, it add's weight to the bike and it also drains the power plant of torque and horsepower with the added work of driving the water pump system. And also, yes, I like the Harley for what it is and has always been, good, bad or indifferent! If I ever want a big ugly water cooled bike I will buy a metric. Other than that, I can't think of a reason why I would never buy a water cooled Harley!!!

 

IIRC about ?20? years ago Harley was faced with water cooling to meet new EPA sound requirements. Seems like HD had some politicians come out and listen to their *stock* bikes and the politicians left agreeing that the bikes were not too loud and altered regs so the bikes would not need water cooling. I guess now the reason is tailpipe emissions.
So, now I am wondering if there will be a Screamin Eagle kit or something to air cool the new bikes?

 

It would not surprise me but I don't believe Harley will ever go completely liquid cooled.

 

I don't believe they will water cool Harleys anytime soon, they will fight tooth and nail to stay air cooled.. The biggest problem with water cooling a Harley is not the ugly radiator, it will make the engine itself ugly.. No longer will they need the big fins on the jugs and cylinders.. A very large part of the Harley look is the exposed engine with giant air cooling fins, it will be very difficult to pull off a good looking water cooled Harley..

I honestly don't care if they do water cool Harleys as I don't buy new models anyway, they lost me with the 50 pound wire harness, multiple sensors and computers, and fuel injection..

I will keep running my EVO's until I die anyway.. My oldest EVO is 26 years old, runs strong and reliable with no complaints.. I can also repair it if need be on the side of the road with basic hand tools..

If they water cool Harleys, It will just increase the value of my stable full of EVO and TC powered Harleys anyway..

Imagine the added fail points of a water cooled Harley, hoses, pumps t-stat, ect.... Water cooling is not more reliable by any means..

 

Government mandated emissions, mostly. Keeping operating temperatures within a narrow range means that efficient combustion can be better controlled, and mechanical operating clearances will stay within a narrower range.
Not much Harley can do, but comply.

 

just because they water cool the heads doesn't mean they have to get rid of the fins. if the water is contained to head circulation only i believe there would be minimal issues. hiding the rads in the lower fairings works for the touring rides, but what about the open frame bikes ? putting the rad under/behind the oil tank on the softail models with the proper ducting i don't think any one would ever know it was there.

a lot of people complain about high cyl head/eng temps due to eng size and emission requirements yet will complain about a possible remedy to the problem.

lets face it folks.. gov regs on emissions is not going away.