I removed the doors from my lowers, seems to help a bit.

 

StreetGlide trikes do not have lowers, Ultras do. Ultra 2 wheels have lowers, Classics, RoadKings Standards do not. The lowers are really not an issue as far as motor cooling goes. They are for leg protection of the rider. If they were an issue for cooling, then all dressers would have them or none of them would.

Bill

 

+1. You are correct. I like them for leg protection.

 

The left lower saved my knee from a rock that came from a semi's tire and god only know what else that's add chipps on the lowers.
Butch

 

funny you brought this up. i've had my flhtk with vented lowers for over two years now and never opened them thinking whats the big deal. well, it was 95 here in MA on sunday and while driving i reached down and slide them both open. there is definitely a rush of new air that comes up now from underneath, close to the bike and provides a lot more ventilation. i can't help but think it provides more air or ventilation to the motor too.

tin

 

Just the shape says it will put more air to the center area of the bike. I don't know how much pressure is there to push it past the cylinders, but there is a definite air scoop shape to them.