Took a nice ride down to Ocean City, MD yesterday with my buddy who rides a Harley Road Glide. Headed back, we maintained a pretty good pace with him leading the way. Then I hear a strange "metallic rapping/tapping" sound. Seemed less when I'm under load. When I let off the throttle, it's accompanied by a raspy rattling sound. Pulled over to do an inspection. Tapping seems to be coming from lower rear cylinder, rasping rattling (when I let off of the throttle) seems to be coming from top of rear cylinder head. No smoking and seems to be no degradation of power, although I didn't really get on it after I heard the noise. I limped in home last night and put it in the garage. To make matters worse.. I have to hear all my Harley Buddies talk about how they I broke down trying to keep up with the Harleys! SMH. I'll try to do a sound clip later today.