Motorcycle Questions? Ask a Mechanic.
Hi and welcome to JustAnswer,Thank you for the question and your patience. Should you still need assistance for information purposes only...Initially, proposed preliminary checks (if have not been done):
If the starter motor spins but engine would not turn over, then it would be an internal hardware issue or more particularly, likely suspect would be the 1-way starter gear (clutch).
Perhaps the video HERE may shed insight.