About done rewiring my chop, fuse question

[jurob]

Removed the factory harness, using the simple diagram from this site.

Wire that goes from reg/req goes to the battery with an inline fuse. Diagram shows a 20 amp for the main fuse, my keyed ignition switch is rated up to 15 amps.

Will a 15 amp main fuse work instead of the 20?

This is the red wire that goes from the reg/req to the battery and also splits from that wire to my keyed ignition swith than to my fuse block.

 

[Stone]

I ran a single 15 amp fuse when i first wired it up (all I had). It worked no prob I wasnt going to change it until my buddy laid the bike down in the field and the RPMS went flying. wouldnt start after that, some how it blew the fuse?!? I threw a 20 amp in because thats what the diagram showed. Havent had a prob since, and I have no clue what my keyed switch is rated at

 

[pumps]

Breakers and fuses are there to protect the wires. The wires and fuses are sized together. A fuse will blow instead of the wire melting. I don't what size wire you are using but be sure they are rated the same.