Each year, there are some things you can always rely on: Marc Marquez will be MotoGP champ; There will be a new Royal scandal; Saints will be struggling to avoid relegation and...the Evo's rear brake will need bleeding...again!
With previous bleeding, I've always removed the caliper and flipped it so the nipple faces upward in an effort to remove all the air.
Flipped caliper
However, despite this and, even though the brake works perfectly after bleeding, you can guarantee that, sooner or later, the sponginess will return.
I think one of the reasons for this may be the master cylinder's proximity to the exhaust. There's no heat-shielding for the cylinder or pipework so continued exposure to the exhaust heat may well contribute to a gradual deterioration of the fluid.
With the bike laid up over winter, I noticed that pedal travel had increased again so I was determined to try to achieve a longer term solution.
In an effort to achieve this, I've employed the following strategies:
• Get the caliper higher than the ABS
• Use a MityVac to keep the fluid (and any air bubbles) flowing
• Switch to DOT 5.1 from DOT 4, which should resist high temperatures better as its boiling point is 260° against 230° for DOT 4.
Taking the caliper off is straightforward enough once the exhaust and wheel have been removed. To get it higher than the ABS, you first need to detach the two wire hose guides. The top one is visible and is held on by the hugger mounting screw and the second one is on the underside by the right footrest. Both screws are 4mm cap heads and should be Loctited on replacement.
With the hose guides removed, you can pull the hose from the black plastic guide on the underside of the swinging arm. There's no need to remove the guide, there's enough flex to get the hose out, (and back in again), in situ. Just note that there's a black cable tie at the engine end of the guide, which needs snipping off.
With the caliper free, pass it up between the swinging arm and engine and there's enough hose to move it above the ABS unit with the bleed nipple uppermost.
Ready for bleeding