I recently purchase a 2001 YZ426 that did not run. Took it to Yamaha and asked them to go completely through it, ultimately they rebuilt carb, changed oil, adjusted valves, flushed radiator, serviced air filter, etc. I took it out and noticed a pretty significant clunking at idle and low RPM, goes away with some throttle, runs strong with massive torque, starts on 1 or 2 kick every time. Haven't owned a thumper before. Wanted to see if this is normal before I take it back to the shop.