Mushy rear brake

My buddy has an '09 AE. He said when he brought it out of winter storage the rear brake had deteriorated. He said there is 2.5-3 inches of pedal travel before he gets engagement, and even then there isn't much stopping power. He has had it to two qualified shops, one a Yamaha dealer. Both say they completely bled the system but there has been no improvement, I'm told. Both shops speculated there may be a problem with the master cylinder, but both also said they have never heard of such a failure with an FJR. I told my pal I'd post up and see if Forum wisdom might help zero in on the problem. My friend is in a rough financial spot and hopes to avoid a big expense. Can y'all help?

While not common, this problem seems to be reported more often these days. The root cause seems to be issues with bleeding the front linked brake properly. I can see a non-Yamaha shop making this shoddy mistake but a Yamaha shop should know better.

Can the brake pedal be 'pumped up' until it gets firm? (Repeatedly and firmly press on the brake pedal.) If the pedal can be pumped up the rear brake master cylinder is good.

In this order:

1. Bleed linked front (center nipple on right front caliper)
2. Bleed rear
3. Repeat if necessary

The front brake is the most distant and should be bled first.

There are things that can make bleeding brakes easier but they are not necessary. All you really need is a brand new, unopened bottle of brake fluid, IIRC a 8mm wrench, preferably a box end, a short piece of clear tubing to reach between the bleed nipple and a waste container.

Remove the cover from the brake reservoir and verify there is brake fluid, fill to the fill line if necessary. Put the box end wrench on the bleed nipple then put the hose on the nipple and put the hose in the waste container. GENTLY, gently, gently push down on the brake lever so as not to geyser the master cylinder. Keep pressure on the pedal as you open the brake bleed screw, the brake pedal will drop down -- CLOSE THE BLEED SCREW -- and only then let the brake pedal ease back up. Push down on the brake lever (gently) and crack the screw....... Do this until no air bubbles comes out of the brake caliper. Add brake fluid to the master reservoir as needed to keep it from running dry.

Once the front is done, do the back brake caliper using the same technique until no more air is expelled. Replace the brake reservoir cover

Try to pump up the pedal, this is the first thing to try. If the pedal firms up the master cylinder is good. If the pedal doesn't firm up then try bleeding. If that still doesn't fix it come back and let us know, there are other things that can cause a soft brake but we need to get the basics out of the way first.

Right. What you wrote is surely correct. I have read that bleeding the linked ABS brakes is trickier than usual and needs to be done right. I'll pass this along.

Okay, sent Ionbeam's suggestions to my pal and he wrote back:

"Tried pumping the brakes again. It's a no go. Still lots of travel and mushy.
Off to Yamaha when I have $ again."

Try tying the front brake lever tight towards the grip.(I use a Velcro strap) Wedge something or hang a weight from the brake peddle. Do this overnight and see if there is any improvement. On most brake systems it will bleed air out into the reservoir fixing the soft peddle problem. It's free and easy. Works very well on the Gold Wings complicated system.