04-21-2015, 11:03 AM
(04-21-2015, 07:49 AM)thessler3_imp Wrote: I do not think air-cooled bikes are dead in the US or anywhere else. I read a lot of historical technical journals on engines, including WWII aircraft engines. Water cooled engines are capable of delivering 3% more power than air-cooled engines. I will willingly give up 3% of power for the simplicity of air cooling. Many riders still want air-cooled motors and they will get them. The manufacturers build what sells, even if they sometimes make models that do not sell very well, they keep trying.
Gentlemen,
Perhaps 70 years ago as regards aircraft engines that are operated at fairly constant power levels and can rely upon a steady 250 MPH flow of cooling air that is true. But that formula doesn't apply to motorcycles today. Modern motorcycle engines capable of passing EPA emissions can probably produce 100% more power if they are water cooled. Air cooled engines must be in a mild state of tune to pass emissions today. This is why the CB11 is not a 750. Even at 1130cc it still produces only 87 horsepower. The new Yamaha R-1 has a smaller water cooled engine that puts out 200 horsepower. That's a tad more than 3%. Because the CB11 had air cooling as a design feature and knowing it needed to be a solid performer despite the required mild state of tune, displacement was bumped way up to 1130cc.
As far as air cooled bikes continuing to be produced I agree with you there but I think they will be small displacement, low power bikes like the Honda Grom and other lightweights. Even small displacement dirt bikes are water cooled today.
Harley Davidson will hang on to it in mildly tuned big twins as long as they can but I don't see another 4 cylinder big bore air cooled street bike after our CB's. I hope I'm wrong.
Chip