12mm front master cylinder ?

Does Kawasaki make a 12mm piston bore front master cylinder for 7/8" handlebars ? Reason I ask is that I also have a 75' Honda CB 750 K5 besides my 77' KZ1000A that I'm trying to better the front braking of it . I read that the stock bore diameter of the M/C on my Honda is 14mm and going to a 12mm bore would enhance the breaking performance ? Bike is stock with a single disc brake and haven't gone to dual brake rotors yet as I did on my KZ.

I thought that the EX500 had a 1/2" piston bore M/C which is close to 12mm ?

Just thought with all the Tech Guru's on this Forum, might find a good answer

If you go to ebay and look at photos most of the time the size is cast into the master body.

I've looked at a bunch of single disk Fr br master cylinders on eebbaayy & most of the Japanese oem have 1/2 cast into them. Many are mfgd by Nissin which seems to be a common supplier to the Big Four. I got one for pretty cheap & in vg condition from a late model Honda but haven't installed it yet. Below is an an example. I also got a new lever for it.

CBR500 mc .... ... ..... Honda oem lever

1/2 = 12.5 mm. usually for single disk .... 1/2" is actually 12.7 mm
5/8 = 16 mm. usually for dual disk

14mm is a popular size for UJM's of the KZ era. Typically used on single disc applications.

If moving from 14mm to 12.5 you can expect the hand pressure to go down for any given level of braking force. The lever will travel further and may feel spongy though. If making a mod like this is doubly important to use good brake lines like teflon/stainless. The 40 year old rubber lines should go in the trash bin regardless of what size master you use though.

Martin, I see that the CBR500 mc is a 1/2" piston bore but I don't think it has a provision for a screw in mirror mount ?

Nessism, On this Honda K5 I have, I was planing on changing out the brake lines to stainless. Bike currently in it's stock configuration, the brakes are not very effective in stopping even with New pads.

I found an Old mc that I had laying around. I thought it was from an EX500 but has no provision for mirror mount ?

The CBR500 mc has a plastic plug in the mirror orifice & the orifice threads are the same as the KZ mirrors.
That mc is fairly common with plenty available on eebbaayy in good condition. New rebuild parts are available.
There are other similar front brake master cylinders from other Japanese mfgs.

The piston bore & handlebar mount are parallel to the reservoir cap, so it's intended to be mounted level.

The Euro bars on my bike are angled downward, so the Honda mc won't be level. I'd prefer one with a slightly angled mount, but I didn't find anything suitable at the time. Most of the angled master cylinders are angled too much, because they're usually mounted on Ltd models or cruisers.

The Euro Bars that I'm running on my Honda are the one's that the European 71-72's had on the 750's. I purchased them from David Silver's and looks like the ends of the bars are angled up. Should work with this M/C ?

I use the same handlebar and like the lower style. No problem with my 14 mm MC (single disk) and i like the handling.

Nice Bike ! Would love to bring my 77' KZ1000A up to that level . What all have you done to the motor ? That's my next plan of attack on my KZ.

Motor got new seals, gaskets, cam chain and cam chain guide sprockets and guides, ported z1000J head with new valve seats for bigger valves (BMW), new valve guides and valve stem seals,adjustable cam sprockets, APE top chain sprocket adapter , APE clutch needle bearing push rod, oil pan swing door mod,......
Needs a big bore 1100 ccm kit or more and some RS 34 carbs ,(on the to do list for the next year).

I don't know what front end and swing arm that your using but what are the gauges your using ?

I'm changing my front 19" wheel to an 18" and with recommendations from the Forum, have purchased a 24-T speedo gear. Don't know if it will fit stock speedo gear assembly and how difficult it is to change out but will see ?

If not, what speedo and tach assembly are you using ? Does it correct for speedometer error ?

Hello kzdcw

Front end, wheels and brakes parts are from a ZX-9R Model B (94-96).
I bought a cheap donor bike for my Z1B project.



Swing arm is made in Germany by Krüger & Junginger
www.krueger-junginger.de/html/alu-schwingen_k_j_profil.html




Speedo and tach is a KOSO RX2N+ GP Style with lot of functions like speed and rev limit flasher,oil and engine temp sensors.
It has a inductive speed sensor that count the speed signal from the rear or front break disk screws.
Number of screws (Signals per one wheel rev have to set into speedo) and the tire scope input ( for me 1979 mm )
for the correct speed displayed. Easy to install and it comes with all parts you need.