Hey guys my brother bought a 98 yz400 yesterday. the bike refuses to run at low rpm, you gotta stay on the gas to keep it running. it likes to crackle and pop back through the pipe, now i have never rode one of the newer 4 strokes until he bought this it seems like the pipe gets very hot id say if it was dark out it would glow. it will idle at a higher rpm if the choke is pulled. so i assume the carb is stopped up leaning this thing out but i thought i would ask since i know nothing about these bike's. thanks