Motorcycle Repair: Idle to high, clock wise, lifters

Question
I have a 2004 Sportster XLH 883. After warm up engine idle seems to be ok, after riding 10 - 20 miles the idle is very high, what would cause this? The exhaust smells like it is running rich. If I shut it down for 5 minutes or so the idle goes back to normal. I'm new to HD so I'm not sure about a lot of things but, the engine seems to be noisy sounds like the lifters are rattling is normal its has done this since knew so I assumed it was normal. Also I want to change the exhaust to give it a little more sound any suggestions for this? It only has 500 miles on it.

Answer
the idle screw is to the left of the carb. Ride the bike and get it to operating temps and adjust your idle by backing off the idle screw counter clock wise. white brothers e-series 2 into 1 exhaust system is the best on the market for you bike. Johnny