Had that same EXACT rattle that I have been trying to get the MOCO to take care of. Has been there for over one year. After having to three different dealers about this problem, I finally dtropped off at dealer in September and left bike so they could hear noise ( worse when engine cold at start up), they had MOCO rep look at it also. The MOCO finally agreed to have top end torn down. They found the piston clearance was at maximum specs. MOCO gave them authorization to bore .010 oversize and do a "custom fit" on that clearance so they could put it to the low side of the specs. The dealer tried to get the MOCO to authorize a valve job at same time, but that was declined. My dealer stepped up to the plate for me and did the valves at no expense to me, as they felt there could be a problem there also, and did not want to take the chance of putting it back together without seating valves. That turned out to be a smart decision, as they found the valves were not seating in the heads properly and were creating a "click" when seating back down on the heads. The problem is that the MOCO had a 7 week back order on the pistons. I just got the bike back yesterday from a 9 week lay up in the shop. I rode about 100 miles yesterday ------ that noise is eliminated!! My dealer wanted to clearance the pistons themselves, so they could keep that clearance tight. They said on the assembly line there is to much chance of not keeping those critical tolerances tight on each and every set, and with the short skirted pistons, there seems to be many problems out there with piston slap. That must be why the long back order?? They tried to get a new set of jugs from the MOCO before they went to the final stages of boring, but the MOCO denied that one. Dealer wanted to be able to bore a new set of jugs for stock pistons, but had to do the .010 oversize instead. They also stated that they thought the valve problem was most of the noise. Whatever the case is, the noise is gone, and now I can wait for the next problems to arise. They did the brake light switch recall, so that one is taken care of also. I did just contract with Legacy H.D. and extended the warranty for 5 more years after all this happened. If you have this same noise, take it in and MAKE them repair it. My dealer even stepped up to the plate and gave me a 2011 loaner for one weekend so I could do a charity ride , at no cost to me ( that bike did not have the noise, but it was a 103). Their service is superb. I can not say the same thing about the MOCO, as they like to fight you to the end.