I have a '97 Heritage FLSTC that I recently purchased. It has the 1340 EVO with stock carb, K&N filter, and new Andrews 220 Cam and lifters/rods. I didn't bother checking the plugs right away as I've only had it a few weeks and only put about 70 miles on it. I changed the oil, some small bolt on parts like switch housing, adjusted the clutch, replaced timer cover. The problem: Went out to fire it up today for a ride, and it sounded awful and backfired. I felt the pipes and engine and only the front cylinder was firing/getting warm. I pulled the plugs and they were both black and a little wet. I cleaned the plugs off, sanded the contact points with some fine sandpaper, checked the gap ( .040) and reinstalled. Both cylinders were firing now, but it still sputtered a little and popped. After 1 minute of running, the plugs were fouled again and wet. Did I do something wrong? Thanks for any help.