The BSA WM20's were originally fitted with taps that had an 1/8 bsp thread both ends. Lots have been converted over to 1/4 x 1/4 now though.

For reference, a 1/4 BSP thread has an actual outside diameter of 1/2".... 1/8 BSP is 3/8"

Ron

email (option): ronpier@talk21.com

Hi there Alun

R.e. WD G3L petrol tank taps. Just measured the taps on my WD G3L & the inlet (Filter end) is 1/8 BSP While the outlet thread is 1/4 BSP.

Chris Moore

email (option): millspray@yahoo.com