One other thing you didn't mention (Maybe I didn't see it scanning the thread) was when the start problem takes place? Was it with the unit in neutral, or in gear with the clutch engaged, or both?
If in neutral, the starter relay finds it's ground through the neutral switch. If in gear, it finds ground through the clutch switch then the sidestand switch. If both, then chances are it isn't the ground for the starter relay.

Do you have a starter circuit print?

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