APRILIA TUONO V4 R 2010 Service Station Manual page 428

Braking system
Rear
Any air trapped in the hydraulic circuit acts as a cushion, absorbing much of the pressure applied by
the brake pump and minimising the braking power of the calliper.
The presence of air is signalled by the "sponginess" of the brake control and by poor braking efficiency.
CAUTION
CONSIDERING THE DANGER FOR VEHICLE AND RIDER, IT IS STRICTLY NECESSARY, AFTER
REFITTING BRAKES AND RESTORING THE BRAKING SYSTEM TO THE REGULAR USE CON-
DITIONS, THAT THE HYDRAULIC CIRCUIT BE AIR PURGED.
NOTE
THE VEHICLE MUST BE ON LEVEL GROUND TO BE PURGED. WHILE PURGING THE HYDRAUL-
IC SYSTEM, FILL THE RESERVOIR WITH THE NECESSARY QUANTITY OF BRAKE FLUID.
CHECK THAT, DURING THE OPERATION, THERE IS ALWAYS BRAKE FLUID IN THE RESER-
VOIR.
•
Remove the rubber protection cover
from the bleed valve.
•
Insert the transparent plastic pipe in
the rear brake calliper bleed valve and
insert the other end of this pipe into a
container to collect the fluid.
•
Remove the rear brake fluid reservoir
cap.
•
Operate the brake lever and then open
the bleed valve on the calliper by a 1/4
turn to let the air escape.
•
Close the bleed valve before reaching
the end of travel of the brake lever,
then repeat the operation until air no
longer escapes.
•
Screw the bleed valve and remove the pipe.
•
Top-up the reservoir until the right brake fluid level is obtained.
•
Refit and lock the rear brake fluid reservoir cap.
•
Refit the protective rubber cap.
BRAK SYS - 428
TUONO V4 R