Check your radiator caps!

I've had two radiator caps on my Kawasakis crap out in the last couple of weeks. Both the centre section where it rivets to the top section come adrift allowing the centre bit to wobble and the top bit not to seal. One was my ER6n, which I bought new- it overheated during a course and my 01 ZRX had been losing coolant- could smell it when the bike was cooling down. About $50 odd bucks from Kawasaki. (and who knows if they are in stock or a 3 week wait from Japan) OR Repco equivalent- $9.50 and easy to get.

Supercheap auto have suitable caps too.