Size Matters? (Rear master cylinder)

Wow, I assumed that all of the trapezoidal MC's were the same.

Do you know if the rear MC's were switched too?? I have 2 rear MC's that look identical, but one has 5/8 cast into it and the other 14. Do you think that's 14mm??

79MKII wrote:

...Do you know if the rear MC's were switched too?? I have 2 rear MC's that look identical, but one has 5/8 cast into it and the other 14. Do you think that's 14mm??

Per FSM, the rear m/c introduced on 1976 KZ900-B1 LTD is size 5/8. And size 5/8 rear m/c continues with 1977-1979 KZ1000 models.

Sorry I don't know about rear m/c sizes in 1980 and later. Would have guessed continuing with 5/8 after 1979, but would concur with your thinking the 14 means 14mm (subject to actual measure of bore diameter).

Am thinking the smaller 14mm rear m/c is more sensitive (having more braking power with less pedal pressure) when compared with larger 5/8 size m/c. And therefore easier to "lock up" the rear wheel when braking.

EDIT: The Brembo rear caliper may be designed for optimal rear braking performance with a 14mm m/c.

Good Luck!

Post edited by: Patton, at: 2008/02/20 07:57

Thanks for all of the info guys. I'm starting a new thread for the Master Cylinder ID. I might want to rebuild the 14mm unit but I'm not sure what bike it came from originally. I also plan to disassemble and directly compare to my stock 5/8" MC.
Here's the new posting:

New Thread Here