Dodgy brake behaviour

Once again, the front brake is behaving oddly. Some of the time I have
to pull it right in for full effect, other times a slight press does
the trick. The calipers have been cleaned recently, and should not be
sticking (they don't seem to be). It this likely to be air in the fluid,
or something else?
Thanks.

 

Sounds highly likely that it's air in there somewhere.
Stick a load of elastic bands around the lever (obviously so the brakes
are on) and leave it overnight, this will compress the air bubbles
(hopefully) and allow them to float up the pipes and into the reservoir.
Obviously then, you'll probably need to top it up.

 

In uk.rec.motorcycles, Milo Thurston said:

Try squirting some WD-40 (not too much) on the rubber bit of the master
cylinder where the piston gets pushed in by the lever.

 

Don't Try squirting some WD-40 (not too much) on the rubber bit of the
master
cylinder where the piston gets pushed in by the lever.

 

In uk.rec.motorcycles, Klaatu said:

And why not?

The cause may not be the same, granted, but when I had those symptoms (a
creaky feeling from the lever) it sorted it out a treat.