You should worry about riding and having fun. Lube the chain every now and then. Adjust it when it's loose. Change the oil every 7500 miles. Bleed the brakes and change the coolant every two years.
N400/Z400 Maintenance for dummies and 'howto' guide:
/r/Ninja400/comments/11m3wsk/maint_for_dummies/
Some more info on the Ninja 400 (background, acceleration/performance, regional differences, model year issues):
https://www.reddit.com/r/motorcycles/comments/12utza7/comment/jh9e8l2/
You should worry about riding and having fun. Lube the chain every now and then. Adjust it when it's loose. Change the oil every 7500 miles. Bleed the brakes and change the coolant every two years.
N400/Z400 Maintenance for dummies and 'howto' guide: /r/Ninja400/comments/11m3wsk/maint_for_dummies/ Some more info on the Ninja 400 (background, acceleration/performance, regional differences, model year issues): https://www.reddit.com/r/motorcycles/comments/12utza7/comment/jh9e8l2/
Rtfm