I put in ear buds and turned em up. I have some pretty messed up ears.
It still sounds clickity to me.
When the throttle is open and burning fuel is pushing against the piston, rings, etc, the piston wrist pin is always pressed toward the crank.
When the throttle shuts, I think there isn’t as much pressure up top and the conrod has to pull the piston back down.
Any slack in any bushing or bearing on the conrod will make a noise when the loading transitions.
Could just be something loose rattling on the bike. Safe thing would definitely be to pull the cylinder and check for any play.
Hold the flywheel at different positions and see if you can push/pull the piston and get any play.