My buddy has a 03 yz450 that has no first gear. Take off in first and it clanks and neutrals out and then slams back into gear. I haven't ridden it but other people can verify it. Anyways....he brought the bike to my house he pulled the motor and tore it down. Only thing he saw was a nut that had come loose on the gear that is turns the clutch basket gear. He is determined that was the problem I told him it might have had something to do with his knocking noise but not the trans. Didn't see anything wrong with the tans gears(stripped teeth) so after doing some searching it sounds like a shift fork problem. Does this seem correct?? Where is the 1st gear set located in the trans?? I will look at it tonight for signs of wear on the gears/dogs from slamming in/out gear. My buddy is still dead set on the loose gear causing the problem, I respectfully disagree though. Any thoughts?? Also need to locate a good used RH case(the one the clutch cover bolts to) as the loose gear damaged it pretty good if anyone has one layn around.