Well for what it's worth I think you either have air or moisture in the brake fluid. 
 
It's hard to tell from the photo but does the fluid look a little bit cloudy 
 
when you look at the sight glass ? If  the fluid doesn't look clear and bright 
 
then miosture is the problem and you should change the fluid. If the fluid is 
 
OK then the brake needs bleeding. I have a YBR and can tell you that there is 
 
no way to adjust the brake lever travel. One piece of advice is that if you don't 
 
feel confident to sort the brake yourself then get a dealer to do it for you. You 
 
 have to be able to rely on the brakes as you may pay a much greater price 
 
than an hours labour if they dont work when you need them to.