Mikuni carb vacuum pipe o-ring

[biodegraded]

Does anyone know the specs for the little o-ring that is sandwiched between the cap and vacuum pipe on Mikuni carbs? I measured something in the neighborhood of 4mm ID x 1mm thick, and I don't think size is too critical, but thought I'd see if someone here knew the OEM dimensions.

Regards,
Keith

[Mustang]

no idea off hand , but 4x1 mm should work fine