Can the pilot jetand pump nozzle be changed with carb still on the bike? I know you remove the float bowl, but I'm wondering if the carb should be turned upside down when doing so to prevent anything from falling out, or to keep the float in place.

 

i've always pulled mine off to make changes. I've only changed the main jet
with the carb on the bike. Also be carefull with the float bowl screws,
they are soft and very easy to strip the screw heads.

 

You can do everything on the bike, but you will have to lift the tank and loosen the choke cable to get all access to the top needles.

everything else comes out of the float bowl.