I just got an '02 520 exc that has an engine rattle when in the "0" zone (little or no power or compression to the rear wheel). Also does it if you lug the bike (needing to be down-shifted). Sounds like rolling a coffee can with a handfull of marbles in it. Is this normal for these bikes? My brand new wr-450 yamaha does the same thing but not quite as bad. AFTER POSTING I SAW THE LINK TO SIMILAR POSTS, I GUESS I NEED TO LEARN HOW TO SEARCH.