ST Front MC bore size?

another noob here with another question about my unicorn KZ1000ST.
What is the stock bore size for the front master cylinder on the shafty bike? I just got a shaft bike as a my winter project and it came with an aftermarket, 5/8 bore master cylinder. It feels like crap; long travel, little feel.
Not sure if its the rubber brake lines or did the PO just install the wrong sizes MC.
All I can find out through the search is the PN of the MC but not the bore size..
TIA

I'm pretty sure most dual disk KZs are 5/8. Partzilla & eebbaayy photos can be handy for stuff like this. I looked up the stock master cylinder & checked the cross-reference at partzilla. Then searched the relevant info on eb. The mc photos I saw on eb have 5/8 on the underside.

5/8 = 16mm. 14mm may be suitable as well, but 16mm is closer to 5/8".

martin_csr is correct; the master cylinder bore size for the dual front disk bikes is 5/8" (see 1st pic below). You may have air trapped in the brake line. I recommend you change the brake fluid and be sure to bleed the brakes so there is no air in the lines. The 2nd pic below shows my KZ650-C1 brake lever pulled in as far as it will travel - the brakes work very well. The entire brake system on my bike is stock. Ed