Main 20amp fuse flows when I hit starter button. With Ignition switch on everything seems normal - dashboard lights/lights work etc.
Attached wiring diagram. Seems to be a fuse between starter button and common to CDI - it is ok. Does that mean issue is with the hot side thru the Starter/Aux starter relay.
Could it be either a bad Starter relay or the Aux starter relay? Or the wiring? The CDI seems ok - but it doesn't get the juice as the fuse blows.
Any help would be appreciated!

 

That is one weird wiring set up. Normally a thick red goes direct from battery to main solenoid, not going through fuse or ignition switch as shown on the diagram. I would check the starter motor is OK and, if it is, feed the wire, top one on the drawing, direct from main solenoid to battery pos post, by-passing the ign, switch and main fuse. Then see what happens when you press the starter button.