I have a 03 vtx1800r, good battery, 12 v to solenoid still no start. no click, no anything when start button pressed?  

Try jumping the solenoid by placing a wrench or screwdriver between the two terminals on the solenoid. Be advised, you may throw a spark or two. If the motor turns over, you'll need to test your safety switches (run/stop, clutch, sidestand, etc) and also the solenoid itself to determine what exactly is causing the problem.

HTH