hi. in my cbr250rr diagram we can see our ignition switch like below (showed in red arrow)

so we put the key in to the ignition barrel and turn it clockwise as usual. the light comes on as we expect.

my question is what does happen inside the barrel when we put the key and turn it clockwise? does it complete the circuit path between BAT and IG as wee can see in the diagram or doe it complete the path all across BAT-IG-FAN? also why the fuse which relates to the radiator fan has a separate path (FAN) in the ignition switch? thank you.

 

Yes...key on means connection to IG and FAN. Fan likely has it's own connection on the switch due to the large current flow.

 

than you got it

 

Just a little video to look at, and at the bottom of your wiring diagram you can see the Switch Connections and how the bridging works across the wires

 

thank you. watched the whole video and it's very informative.