The early KZ suffered gearbox, piston, balancer and camchain faults. Z400’s reliable for the first 30,000 miles when they suffered similar problems. Z400B gutless below 5k, above vibrates badly. Z440 best of the bunch with few problems for the first 35000 miles. Heavy vibes mean the chain driven balancer’s on the way out. Laid back for a Jap twin, capable up to 80mph. Chassis and caliper rot will have eaten most bikes alive by now. Also Yank imports..