Start with the basics, don't overlook anything and verify all components. First, check the fuse(s) and check battery voltage-above 12.5 volts should be good. Second, check for power at the small terminal of the solenoid while holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). If your solenoid is a four wire solenoid, check both small wire terminals as one is ground and the other is power from the ignition switch. Third, check for power from the battery to one of the large terminals on the solenoid. Fourth, check for power on the other large terminal of the solenoid while holding the key in the start position (you may need an assistant to sit in the seat to override the safety switch). Fifth, check for power at the starter while holding the key in the start position (assistant again). Sixth, check your ground circuit back to the battery.
Since you replaced virtually everything in the starting circuit except the wiring, you may have a wiring problem but that will show up with the above checks at the point where power is interrupted. Perform the above checks and report back with your findings. If you don't know how to perform the checks, just ask and we'll guide you through it all. There are more potential checks to make but I don't want to overwhelm you so do just those items listed and let us know what you find.