Our ninja uses a 14mm rear master cylinder and a (1) 38mm rear caliper, single piston. Ducati uses a 13mm master cylinder and a caliper with 2 34mm pistons....some of the newer ones are 2 32mm pistons. If you look at high end Brembo rear master cylinders, they are sized 13mm, and thats about it....similar to the 1/2" Kawasaki used prior to 2011.
This chart says "VINTAGE" and "FRONT". I thought it would be 1970 useless when I tried to build a master/caliper combo that worked. It turns out, its not, its still totally accurate. Then again, people in the 70's didn't hoard toilet paper...we just worried about the Russians blowing the **** out of us..
If you do the math on those combinations, it ends up where the ninja is 7.37. The Ducati is closer to 12.1 area.....
The chart says, "Single piston calipers are much happier in the 14:1 to 12:1 range" I know he's talking about front brakes, but its so similar its not even funny. I thin it worked because the brake pedal is sized like a brake lever, if you use your imagination. Its not 4 inches longer, or shorter....
I was able to get mine to be @ 12.2, and its awesome. I had more overall power at 13.0, but the pedal was softer.
These numbers are not 100% accurate. The Ninja numbers are, but I rounded off my final numbers.
Most al of the bikes from Japan are sized like this. BMW follows the chart, on their expensive bikes as does Ducati. I totally understand an effort to protect riders from locking up the brake, but when they dialed out the feel, who the **** knows when its going to lock? Then they spend high dollars on an abs system? Based on all i've been able to find, thats why it doesnt work well, no matter what pads you buy, and also why a super sticky, hard grabbing pad sucks.
https://www.vintagebrake.com/mastercylinder.htm