I'm missing one of the three screws that attach the MT110 light on the rear number plate. I know the threads of these slotted cheese head screws are 36, the length 3/8" but what is the diameter (is it 5/32"?). What type of thread does that makes it?
Hi Kostas
Possible threads are
UNF No. 8 (approx. 5/32”) x 36 TPI
BSC 5/32” x 32 TPI
BA no.3 (3BA) which is approx. 5/32” x approx. 35 TPI
It wouldn’t have been UNF originally but some previous owner may have bodged it. BSC and BA threads are both candidates, depending on how accurately you were able to measure the TPI. The motorcycle manufacturer would have preferred to use BSC, but Lucas was fond of BA threads for their components. I think I’m right in saying that the instrument panel on Lucas headlamps is fixed with 3BA screws so try one of those to see if it fits properly.