What causes Stator/charging system failure on the Kawasaki Z400?

Battery voltage at idle, check for dimming lights Estimated fix cost: $200-$400

What causes Throttle body sync issues causing rough idle on the Kawasaki Z400?

Idle quality, hesitation on acceleration below 4k RPM Estimated fix cost: $50-$150

Rattling noise first 10 seconds after cold start Estimated fix cost: $100-$250

Oil residue below fork tubes, soft front end feel Estimated fix cost: $100-$200

Known issues to inspect before buying a used Kawasaki Z400. What to check and how much repairs cost.

SERIOUS

Battery voltage at idle, check for dimming lights

Fix cost: $200-$400

MODERATE

Idle quality, hesitation on acceleration below 4k RPM

Fix cost: $50-$150

MODERATE

Rattling noise first 10 seconds after cold start

Fix cost: $100-$250

MINOR

Oil residue below fork tubes, soft front end feel

Fix cost: $100-$200

☐Cold start the bike, listen for rattles

☐Check charging voltage with multimeter

☐Inspect forks for oil weeping

☐Test throttle response through full RPM range

Generally solid, minor electrical issues worth watching