I had a 94 ZZR600 with a yosh race kit,full duplex exhaust,race cams and a computer and I blew second and third gear out of my bike as they were the most abused gears on the track I used to run. I would say both of you guys need some transmission work on your bikes. both of those ZZR600 are fairly old bikes by now and kawasaki is´t know for it´s transmissions.