Starter clutches are bad; kickstart it, or split the engine case and repair. Sorry to deliver the bad news friend.... I had an '82 KZ750 that had the same problem.:2cents:Electric starter engages with plugs out but under compression it makes alot of noise and doesn't stay engaged.This is on a 78 kz 1000 motor
If i am not mistaken on the kz1000 the starter clutch is behind the stator same as the new z motor the kz zr ltd 750 motors the starter clutch is in the middle of the motor I had to replace one on my zephyr 750:screwy:Electric starter engages with plugs out but under compression it makes alot of noise and doesn't stay engaged.This is on a 78 kz 1000 motor