How to tighten FLywheel Dynamo Nut and Torque SPec

[4_0_6]

I'm having a hell of a time with my 1965 CA77 Honda 305. I just purchased the bike and nothing has been going right trying to get it running again.
Now I feel like I really messed up and I don't know how to fix this issue that just happened.......I left a box end wrench on my flywheel nut while setting my timing and started the bike. The wrench stuck on the brake pedal and the bolt unscrewed from the flywheel. Doesn't appear to be any damage the flywheel or the bolt and washer. I'm not sure if there where any spacers or anything behind the washer though?

Now I have to figure out if there is a way to tighten the nut back on as the flywheel just spins freely. Any suggestions on proper torque for this nut, whether or not there is supposed to be some kind of spacer behind the nut and washer that came off, and if there is any way to hold the flywheel tight and keep it from moving without tearing apart the right side of the motor? Hoping for some good news hear on a simple fix but not holding my breath.

[sky.fred]

The Shop Manuals don't quote a torque figure for the bolt, tighten without exaggeration (around 12 - 15 ft lbs ?)
There are two ways of locking the rotor:
if dismantled, secure with a strap.
If not disassembled, the solution is to put it in gear and using the rear brake, which will lock the rotor sufficiently to tighten it.

[deuce_7]

Also,

Check the Woodruff Key and Keyway on the crankshaft. Might have received quite a jolt.