08 YFZ 450 SE: after engine rebuild, I'm having a transmission issue i can not figure out. engine running perfect, go to shift down into 1st gear, i can hear the shift, i can feel the gears move, but... i let the clutch out, the quad will move about a foot and the rear tires lock up. some times, i won't be able to move the sifter. some times i have to get off and rock it back and forth so i can shift into 2nd. second gear seems to work just fine... shift into 3rd, tires lock up engine stalls. took the engine apart, and noticed some of the notches on gears will hit the notches of the gears next to it... causing everything to stop moving. no damage or wear on any parts inside the engine, none. no marks on the shift forks, yet i can't tell if the forks are good or worn. they look perfect. while the engine is apart, i can line the gears up and spin it all freely. start moving the shift drum, going though the gears for movement and the notches lock up. these should never touch each other. does anyone have any idea what would be allowing these notches to come in contact with other gears? i was told the shift forks may be slightly worn. i was told the force of the gears spinning while the engine was running is what keeps them from touching. either way, my quad still won't move and I've taken this apart 3 times for this one damn issue. its riding season and I'm sick of this just sitting here. i need this forum to help me out... I've asked questions and i have never ben answered.... i need some ideas here... help a brother out.