front master cylinder question

Is there any advantage or disadvantage to using a master cylinder for a dual disc brake on a single disc brake?
Thanks, Jerry

Not a good idea. Brake lever feel will not be as good as when the master and # of calipers are a matched set. Ed

I haven't done the math, but with a larger Fr Br mc bore I think you'll have to squeeze the lever harder.

Word on the street is a 14mm master cylender works well with a 4 piston brembo caliper.

What is the original bore of a kz750 twin with single disc?
Thanks, Jerry

For most bikes of the KZ era the dual disc bikes used a master with a 5/8" bore and the single disc bikes use a 14mm bore master. I have no idea why the mix of metric and imperial dimensions for these parts, that's just the way it was. HOWEVER, there are examples where smaller masters were used on dual disc bikes. I believe some of the later year KZ550 bikes for example. Using a smaller bore master will lead to more lever travel but less hand pressure for the same level of braking force at the brakes. Some people may like this trade off, but others may not since the level feels more "spongy". Using a large bore master will create the opposite situation: the lever feel will be very firm, but you must squeeze quite hard to create the same amount of stopping force at the brake compared to a smaller bore master.

If anyone wants to try a smaller bore master be sure to upgrade your brake line to teflon/stainless at the same time to reduce flexing. Changing your brake lines is something that should be done regardless since 35/40 year old rubber parts are just plain bad. At any rate, the stiffer brake line will reduce some of the spongy feeling at the lever.

Thank you nessism This is just the kind of information I was looking for.
Jerry

jertho wrote: Thank you nessism This is just the kind of information I was looking for.
Jerry

Before going too far mixing two different plungers, pistons, master cylinders and and calipers... read up on Pascal's Laws of hydraulics.