Rear Brake Pedal Drops

Hi ,
new to St1300 bike , have one with 82K miles in overall good condition.
Never before had bike with ABS and this level of complexity of braking system.
Need help to identify or understand problem.This is what is going on :
apply front brake , while front brake applied I push on rear brake.
When I disengage front brake I can feel my rear brake pedal is dropping lower under my feet.
Is it normal?

Re: REAR BRAKE

No, that is NOT normal. The pedal drop after the front brake is released means there is air in one or both of the rear brake caliper circuits and the air is most likely in the circuit containing the proportional control valve and the secondary master cylinder.

No worries, a complete and through bleeding of the system will fix it and firm up the lever and pedal. The fluid should be replaced in any bike with no known service history. Honda recommends it at 12,000 miles or two years but many people take a shortcut and do not remove the left front caliper and tilt it. This ensures they do not remove the air in the PCV and/or SMC.

where can I find best instructions how to do this ( bleeding st system )

DONCZ said:

where can I find best instructions how to do this ( bleeding st system )

Click to expand...

PM me your email address and I can send a tutorial with step by step and pictures.

just finished brake bleeding, my proportional valve was really bad.
during this procedure I found I cant bleed center valve on front caliper ( dry , no fluid at all) . Also center caliper on both sides is not moving under pressure.
I can press it in , but there is no brake fluid behind to push it out.
did somebody experience this ?

My rear brake pedal also drops a bit when the front is pulled first, then released with the rear still pressed. This is even after a full bleed by the book. I think it's "normal"?
For your center front bleeds, you do realize that it's the rear pedal that feeds that circuit?

playfair said:

My rear brake pedal also drops a bit when the front is pulled first, then released with the rear still pressed. This is even after a full bleed by the book. I think it's "normal"?
For your center front bleeds, you do realize that it's the rear pedal that feeds that circuit?

Click to expand...

It's not normal and can be bled out. Odds are that many ST1300s do this however and they owners think it is normal.