my wr400 seems to have a bit of a rattle that wasn't there 100k's (70 miles) ago when i bought it. bike has about 2700k's, (1500 miles) on it. when i got it, it had a nice tight sound, a bit of a mechanical whine to it. just a faint tapping. now it sounds like an xt250 thats done 20,000k's, no whine and a little bit more chatter than when i bought it. it does slightly feel like its not as crisp when you are on the throttle. as far as i know the valves were done before i got the bike, and it seemed like they were. they have no adjustment at all? just shims? could the clearance be out of spec from running rich and lugging it around (and a few short sprints here and there)? or could the cam chain/tensioner be stretched? it has stalled with a bit of a weird 'pop' witch i just assumed because it was so rich/cold couldnt burn all the fuel, and also sounds like a 'tick' noise from the bottom end/cam chain when it happens. i did post on that problem originally but didnt get many answers and gave up, and just assumed it was normal. any ideas? thanks.