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HONDA "F2 vs NT650" Master Cylinder?

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    HONDA "F2 vs NT650" Master Cylinder?

    1991 NT650 SINGLE caliper, master cylinder
    1992 CBRF2 DUAL caliper, master cylinder
    Are they the same part?
    Or is there a "different throw" or "higher compression" for the dual calipers?

    What is the general consensus for using the single disc master of the NT650, to power and push dual discs in the front?

    The issue is I don't have the F2 master cyl. and was hoping to just double banjo the existing hawk master.

    #2
    According to my terribly in-accurate Honda parts interchange list, those are the same part. IIRC a 1/2".
    That's pretty small for 4 pistons.
    You want somewhere around 27 to 1 ratio, caliper piston area to master piston area

    Comment


      #3
      A good way to check if they are the same is to see if the rebuild kits are the same.

      The MCs will be different simply because the Hawk GT has a mirror mount and the CBR doesn't. I am pretty sure they are otherwise identical.

      If you were looking for a support group you're barking up the wrong tree. This place is fulla enablers dude. - Shooter77us

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        #4
        I am no brake guru but I am using a Hawk master with dual F2 disks snd it feels just fine.
        Brian - Richland, WA
        1991 Hawk GT
        1997 VFR

        Comment


          #5
          For an increase in the slave fluid volume, you will need an equivalent ratio-metric increase in the master volume. So, to keep the same stroke and lever ratio, you will need a larger bore. If you keep the same bore, the stroke will increase. You can somewhat dial it with the lever ratio using adjustable levers. But basically that's it. If you're fine with your lever travel, you're good. Otherwise, if you want to decrease your lever travel, get a bigger master cylinder. Ideally, match the actual master used for your calipers or the same size master.

          I haven't measured anything but a large single Hawk caliper volume may be close to the smaller dual piston dual caliper volume. You can get close by measuring the area of the pads. If the stroke of the caliper piston is similar, then the area of the pads alone should get you close.

          Sorry if I got a bit wordy and drawn out. But hopefully, you get the idea.
          Last edited by eyhonda; 08-20-2021, 08:58 AM.
          Eric Y.
          NT663, VFR800 & Vespa LX80
          Yuzon Designworks

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            #6
            F2 and Hawk have 1/2" master cylinder and use the same rebuild parts.
            "Red hair and black leather, my favorite color scheme"
            1952 Vincent Black Lightning by Richard Thompson


            '88 Blue 99% stock SOLD
            '88 Restomod
            '16 Yamaha FJ-09

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              #7
              Originally Posted by eyhonda View Post
              For an increase in the slave fluid volume, you will need an equivalent ratio-metric increase in the master volume. So, to keep the same stroke and lever ratio, you will need a larger bore. If you keep the same bore, the stroke will increase... ...Sorry if I got a bit wordy and drawn out. But hopefully, you get the idea.
              Totally understand, and wordy is good. Perfectly explained thank you.

              Comment


                #8
                Originally Posted by Ziggy View Post
                F2 and Hawk have 1/2" master cylinder and use the same rebuild parts.
                Ziggy, thank you for the confirmation. All the input from all you guys, helps me move forward. Thank you!

                Comment


                  #9
                  Originally Posted by bitzz View Post
                  According to my terribly in-accurate Honda parts interchange list, those are the same part. IIRC a 1/2".
                  That's pretty small for 4 pistons.
                  You want somewhere around 27 to 1 ratio, caliper piston area to master piston area
                  F2 caliper pistons are tiny.

                  "I couldn't afford NOT to buy it!"

                  Comment


                    #10
                    Originally Posted by Captain 80s View Post

                    F2 caliper pistons are tiny.
                    25mm vs 30mm on the Hawk. Of course, the F2 uses two calipers.
                    ASMA #139

                    Comment


                      #11
                      Try a 5/8 (CBR F3, VFR iirc) for a little extra pressure and less travel.
                      88 Hawk GT

                      Talk big. Think small. Do nothing.

                      Comment


                        #12
                        Originally Posted by Gweenz View Post
                        Try a 5/8 (CBR F3, VFR iirc) for a little extra pressure and less travel.
                        F3 uses the same 1/2" MC as the F2 and Hawk.
                        ASMA #139

                        Comment


                          #13
                          Yeah sorry you're right. F3 and VFR gen 4 are 1/2, my Goldwing is 5/8 and CBR600rr (2004) is 11/16.
                          88 Hawk GT

                          Talk big. Think small. Do nothing.

                          Comment


                            #14
                            Originally Posted by captain 80s View Post

                            f2 caliper pistons are tiny.
                            thay are!!!! Freakishly tiny!

                            Comment


                              #15
                              Originally Posted by Toxicwst View Post
                              thay are!!!! Freakishly tiny!
                              I caught a little flack for adding a second F2 caliper/rotor combo to my CB-1 (1/2 F2 master) but when I had two deer run in front of me a few weeks back, I certainly was glad I had them. The feel and modulation is awesome…
                              This forum is entirely dedicated to wasting time and money modifying a slow motorcycle. - joel

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