What size brake master cylinder do you recommend?

[NCAmother]

I have an 850T with dual front disks that I am building.  Can you recommend a good master cylinder for the front brakes? Thanks :)
Nate

[Antietam Classic Cycle]

What calipers? F08, F09, "modern" four piston, or?

[rodekyll]

An 11/16 NISSAN radial m/c would be perfect for dual F08s.

[Tusayan]

One of these 5/8 inch conventional Nissin master cylinders would look the part and work very well with twin old style Brembo calipers, or anything similar. 

https://www.ebay.com/itm/Nissin-Retro-Master-Cylinder-Black-w-Black-Lever-5-8-Piston-17-654B-/172498353604

If the handlebar angle doesn't match the cap angle, you can use a similar Nissin old-style remote reservoir unit, they are all good quality and relatively inexpensive



 

[Shorty]

http://www.vintagebrake.com/mastercylinder.htm     ratio chart

[RinkRat II]

      ^^^^^^^^^^ Yup, 16mm (insert name here) brand is the proper size, zillions out there cheap too!

       Paul B

[Tusayan]

      ^^^^^^^^^^ Yup, 16mm (insert name here) brand is the proper size, zillions out there cheap too!

16 mm is 0.629 inches.

5/8 inch is 0.625 inches

You may find more sold as 5/8 inch - Japanese bikes have traditionally used inch sizes, as with handlebars and wheels.

https://www.ebay.com/itm/Nissin-Axial-Front-Brake-Master-Cylinder-Kit-5-8-Bore-with-Black-Body-/311998313703?_trksid=p2349526.m4383.l4275.c10#viTabs_0

[Testarossa]

I believe the original 15mm master cylinder for the T was (and is) the correct size to drive dual calipers -- it was the wrong size for the original single disc and I long ago replaced mine with a 12mm m/c for better braking power and feel. Big improvement to be had too by switching to braided steel hoses. I also switched to a more modern drilled rotor.

I do think that upgrading the m/c and hoses improves braking enough that adding the weight of a second disc and caliper is pointless.

[NCAmother]

Forgot to say I upgraded to Brembo 4 piston calipers with adapters.  Thanks :)

[rodekyll]

An 11/16 radial will still work, though with a longer stroke for the same work.  I'm using an 11/16 on my 4-pot Brembos.  I like the light touch.  A 3/4 will also work, but will be less sensitive.  05 and up GSXRs used one or the other.  On eBay for cheap.

[Fontain25]

I have used this MC on 4 bikes recently with very good results. It's kind of a generic model that was designed for dual 4 piston calipers ' fits 7/8" handlebar, nice brake light switch and has mount for 10mm mirror ,and has adjustable lever.They are readily available and cheap. https://www.ebay.com/itm/2002-2005-ZX12-ZX-12-ZX-12-Front-Brake-Master-Cylinder/301348910683?hash=item4629cb765b:g:yToAAOSwR0JUOCuD&vxp=mtr

[Dukedesmo]

I use a 15mm Brembo RCS on the LM2 with both front (old Brembo 2 piston) brakes on the master cyl (unlinked) but if you've got 2 x Brembo 4 piston then a 19mm is probably best.


I like the RCS because of the switchable ratio allowing more adjustment but my 916 has a fixed ratio 19mm on 2 x 4 piston Brembo and it works great, only 2 fingers required for stand-on-it's-nose braking.