Motorcycle Repair: carb help!!!!!!, drag pipes, jet size

Question
i have a 1987 sportster 1100 evo engine, when it was bought new my dad had drag pipes put on at the dealership--it has a stock keihin carb and a stock air cleaner, i need to know what jet size to use for drag pipes and a aftermarket air cleaner? and when im riding it and crank the throttle it sputters untill i let off???? what is that about

Answer
You didn't say if you are running baffles or not so I'll assume not.  Try a #45 idle jet and a #180 main jet.  You are going to get more noise and less power with drag pipes as opposed to using a straight through baffled muffler like Drag Specialties, Cycle Shack, or HD Screamin' Eagle II.  You need to open the mixture screw on the back underneath of the carb (if the silver plug is still in there you need to pull it out).  Open the mixture screw 2 1/4 turns and readjust the idle speed when the engine is warm.  Run it on the highway for a few miles and check your plugs.  Black carbon means too rich on the main jet so go back to a 175.