Picked up my 03' WR450 today. Took it right home and did the thermal start break-ins (3X warm-up cool, not too hard when the temp is 27 degrees) and then rode around the block at home. The motor is poping of idle at speed and backfiring constantly under deceleration. Any other 03' WR owners experiencing this? I'm at 6K ft. and the dealer in Denver setup the jetting for this altitude. Past experience leads me to believe the pilot jet is too lean? Any suggestions?