1977 KZ750 float adjustment

How can I check the fuel level to adjust the floats if there’s no nipple to attach a hose to?

Use the Slmjim method....take the bowl off and set the carb on a glass that is wide enough to allow the floats to move freely. Then open up the gas line.

hardrockminer refers to a method we successfully experimented with that we detailed in post # 825825. See the pics toward the bottom of post # 825825 here:
kzrider.com/forum/11-projects/609053-the-wounded-z?start=36

If you wish to use the clear tube method, there's almost certainly a removable drain screw in your carb float bowls. A suitable length of clear aquarium tubing can be "screwed" into the threaded drain screw hole. Trim the OD of the tubing into a short taper carefully & neatly for a liquid-tight fit if necessary.

Good Ridin'
slmjim & Z1BEBE