From memory it was something like 15 mm i.d. x 1.5 dia. in Viton but that's purely from memory of a very old email sent to me. I have emailed the restorer who originally gave me the info and I will get back to you Phil
The guy who told me can't remember sizes. I measured a used gasket & the hole is approx. 17.5 mm dia so 15 mm ID sounds about right for 1.5mm section 'O' -ring Compressed gasket it 1.3mm. Somewhere I have a NOS NP Japanese one and I will measure that.
Anyone else have dimensions to share e.g Gen. Honda , Vesrah, Athena ?
