CVO 8/5/2012Check the wiring for clean, tight connections. The starter motor may draw several hundred amperes during cranking. Loose or dirty connections will cause excessive voltage drop.
Cables should also be checked for correct gauge size. These cables should also be inspected to see if they are too long. Excessive length causes excessive resistance.
See this Starting system simplified diagram. Have a help from an assistant to crank the engine, use a 12 volt light tester or a digital voltmeter, apply it to the starter control circuit.
If there is light or 12 volts and the starter isn't cranking, then the starter is the culprit. Have the starter to bench test for free at the local auto parts stores.
If there isn't no light or no volts, then the ignition switch is the culprit.( may not be the case )
Check the starter relay and position the shifter from park to neutral.