Outthere: I'm so confused by those pics.
Thats a NB O2 sensor, not the WB TunaBuell one?
The pic of the front O2 bung (2010?)
A 16mm Radial Master is a really nice part to put on a ZTL caliper but 2010 bikes had a ZTL-2. That master would be way too small for a big ZTL-2.
manufacturers recommendation. Should work out ok? My brakeing hand only has an index finger and a thumb that's usable so all my braking needs to be close to the bar and not to stiff. If not they said to send it back. The Tuneabuell sensor's installed. The one in the pic is the unit I removed. Throttle & M/C made by Accossato. More research and the stock master is 3/4" bore.
Is your bike a 2010? (Front head pipe bung) Inquiring minds...
Does it have a ZTL-2 Caliper? If so, ya the OE Master is 19mm (3/4"). I tried an 17mm Radial M/C and couldn't even get enough pressure to stop the bike with the lever pulled to the grip!
Curious what you find with yours. Is the lever hard now with the system bled?