Anyone have a source or size for the original D1 gas cap o ring ? Want to replace mine. I have used vasoline several times but time to replace.

 

My favorite on line source for O-rings is The O-ring Store (theoringstore.com). They sell individual pieces fast.

Maybe use your electronic calipers to take measurements (metric or sae)? ID, OD, and CS.

They also sell higher temperature rated o-rings for all the 1/2 inch oil cooler lines.