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GCBC 05-02-2018 10:57 PM

F3 Front brake master cylinder
Alright guys so I finally got back up north after I bought this thing 6+mo ago and saw it for the first time about 2hrs ago. Happy with the looks and rider triangle (once I get the rear sets and other stuff on) didn't start it up until im ready to take it for its first rip to break it in but soon as I hopped on I immediately noticed the brake master cylinder sucks.

Its got the same unpredictable and inconsistent pickup/pressure point issue that the new gsxr 1000 is plagued with as well as my old ducati 821 strip/hypermotard sp was.

I do have abs bike but I imagine the rcs19 is the go to for it as well? will it bolt to the oem clip ons?

Also man, this is a heavy clutch especially for a slipper and on a 675 none the less.

Donsy 05-03-2018 09:30 AM

Really, how old is the fluid in the brake system?
How do you "break" an MV in ?
I've ridden many F3's, they do ok in my opinion, but maybe you're just on a higher level ?
Are you talking track or road use ?

GCBC 05-03-2018 12:20 PM

Well I fired it up for 30seconds just to hear and warm up the stock
Exhaust while I take it off. Quieter than I thought it would be, maybe because I also just fired up the 1098 w the ti arrow on it....

Yeah the brake lever you walk up and squeeze once it travels 35mm w lets say 15lbs then next squeeze it moves 45mm w same pressure and for the next 10squeezes then you come back 2min-5days later and it’s pic n choose same pressure different movement.

On the ducati 821s and the hyper SP you’d be doing 80on a back road grab some brakes and they would be poor but not “shit” by any means and 5seconds later For the next bend at 70 you give it the same brake power you just did and go over the bars initially because lever didn’t move and no it’s not air in the system it was a huge problem with a huge # of brembo products and iirc was a caliper piston suckback problem as well as something w master cylinder. I have felt this on a bunch of bikes but none that are flat out superbikes like there’s except the new gsxr1000 is exactly the same feel.

To clarify this is not the old pump up the brakes and they work better or stiffer lever. It’s some geometry/ratio/piston flow valve issue in the master. It is totally rideable and I would say 95% of sportbikes riders wouldn’t even notice it but out of the A group track guys, 95% would notice and bitch another it. It’s totslly rideable as is so I’ll hopefully get the bike finished up in a week or so because I’ve got multiple other projects I’m working on now and I’ll be able to ride next week while waiting for the parts to come.

Don’t want to do lines just the master if anyone has done this on an abs 675 please let me know what your running and how much it improved please.

GCBC 05-03-2018 12:26 PM

On another note, my 1098 lever is great. Is it a direct swap to this? And vice versa? Actually I would swap calipers as well but Im sure this will mess w the abs somehow. But if they would work Id love to do it

silentservice703 05-03-2018 02:34 PM

Sounds like air in the ABS system to me. There is a Tech Bulletin on how to bleed it.

GCBC 05-03-2018 06:53 PM


Originally Posted by silentservice703 (Post 2485698)
Sounds like air in the ABS system to me. There is a Tech Bulletin on how to bleed it.

other bikes with no abs and same piece of shit Nissin have same feel.

airjawed 05-03-2018 11:25 PM

I know what you are talking about. I felt it on the ducati 959 panigale. My F3 sometimes has it but it'll go away pretty much every time I do a bleed of the master cylinder.

I just live with it but the F3 is consistent. It will grab at a low point but always do that until the bleed. The panigale I could pump it and sometimes it would grab at more of an open position and others at a more closed angle.

I think it is air but it isn't bad really.

Do a bleed at the master and see if it helps. The abs bleed is a bit of a pain due to location and general messiness so do that as a last resort.

silentservice703 05-04-2018 09:06 AM


Originally Posted by GCBC (Post 2485858)
other bikes with no abs and same piece of shit Nissin have same feel.

Interesting as I have those "P.O.S." Nissans on three of my bikes, two regular and one ABS with no modulation issues.

Of course, my hands are probably not as sensitive as yours...but I do find proper and thorough bleeding maintains the consistent feel.

GCBC 05-04-2018 10:09 AM

well everything else is coming apart anyways may as well bleed it but I do want to change the piston ratio for more power. every rcs19 ive felt was as stiff as preachers prick. same w all my mountain bike levers. they literally move like 10mm from off to as hard as you can pull two fingers

silentservice703 05-04-2018 10:37 AM

Mountain bikes have hydraulic brakes now? Who knew?

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