I have an 02 VFR that I've been riding trouble free for the last 7 years. At the end of last season (That was in November) I noticed the brakes didn't feel all that great, so I swapped out the pads. nothing improved with braking and I realized both front and rear brakes are dragging like crazy. I put it up on the center stand neither wheel seems to turn freely. I pulled all of the calipers off the discs and tested them. The wheels spin as one would expect them to with the calipers off. I bled everything out per the FSM and made sure the pistons on the calipers aren't frozen or anything. I reassembled everything and the wheels still spun fine but once I build up pressure in the system it won't let go. What would cause the entire system ( both front and rear) to just lock up like that at the same time? I know these are linked brakes, but it seems odd to have everything choke at once.
I'm having the same issues with the front calipers. Removed the original seals and cleaned the calipers, installed new seals, then replaced the OEM brake lines to the front calipers with two braded lines (eliminating the crossover connection in the front), and now I'm thinking that I need to pull the calipers off and clean/ rebuild them again (not looking forward to that). I also have purchased rebuild kits for both main masters, but in my case the caliper continues to stick even when one of them (doesn't matter which) has been pressed apart thus releaving any residual hyd pressure, so I don't believe it is the master. I have also checked that the active half of the caliper can slide freely.
Likely your calipers are OK...... especially if you already rebuilt them. Check the return hole in the master cylinder is clean/not blocked. It is also possible the return port in the SMC is blocked. See post 12 https://vfrworld.com/threads/diy-bleeding-linked-brakes-w-abs-the-ultimate-guide.38112/#post-623954 In future, don't neglect bleeding your brakes for so long... do it annually and you won't have these problems, lol.
Man, I hate to ask... Where is the return hole? I'm looking at it and I imagine I know what it is, but it would be my luck to manage finding the one hole that should never be messed with and ask after the fact finding that I just trashed the whole thing. I totally do my own stunts.
i'm not much of a "try what you know" path for repairs. But...if fluids are changed with some regularity, nearly all crappy brake feel/working seems to be dirty piston calipers, IMHO.
