so i had an 05 bike with about 10k on it that i recently stripped down after the motor mount on the frame cracked in half. here is my thread about the whole thing thus far: https://www.600rr.net/vb/showthread.php?t=200814
before i started to strip down the bike, the motor still ran, and everything seemed fine. no funny noises, no signs of any problems.
since that time i've taken the motor to get compression tested and i've had some major issues. first we noticed that one of the three wires in the stator plug was corroded (green all around it, and it was disconnected from the actual plug). then we also noticed that there was no gasket on the clutch side.
the first time we went to compression test it, sparks starting flying as soon as we touched the positive lead from the starter to the power source. then we took the little access hole on the clutch cover off to try and spin the motor by hand. the motor spun freely so its not seized.
then we took the clutch cover off, and checked all the gears, rods, cam chain, etc. everything looks fine, nothing is stripped etc. we swapped the starter thinking that maybe it was the starter, but we had the same problem with a different starter.
both starters that we tried spin backwards like they are supposed to, and seem to be spinning at full power when they are of the bike. as soon as we put either one back in the bike however, it can not turn the motor and it starts to spark from the positive lead.
anyone know what could be causing this? something is preventing the starter from turning the motor so is it possible that something could have fallen into the motor while i was taking the bike apart and that is causing the problem?
thanks for the help
edit: also, i have the motor with a mechanic now, and he doesn't know why the motor would spin when you turn it via the access hole on the clutch cover, but why the starter would get locked up...