The clunk is normal. When sitting at a stop with tranny in neutral, the input shaft of tranny is still spinning. When you pull the clutch in, the shaft will still be spinning due to the slight drag between clutch discs. This drag is mainly caused by the fluid. The input shaft is suddenly engaged with a gear that is not spinning when you shift into first gear. This creates the clunking sound.

 

What the hell is an old Limey bike?

 

British, BSA, Triumph.

 

mine bangs, or clunks.
to me its just and indicator and I am ready to roll
like someone said, for some reason, it seems ro be one of the idiosyncrasies of a harley

 

Victory, and some Hondas do it as well IME.

 

I've been told that you should stick to dino oil or blend in the tranny. Full synthetic will make the tranny and shifts louder.

 

It is the clutch plates not disengaging that is why when you put ATF or synthetic in the primary it is easier to find neutral and the clunk is reduced on a properly adjusted clutch. Mine clunks like hell even on the up shifts and at the first 1000 mile service synthetic is going in.
Bob

 

My Yamaha FJR does it everytime.

 

My new 2015 road king is a witch to find neutral and clunk are very loud. My 2005 fatboy was easy to fine neutral and a gentle clunk.