Jeff has a metric O-ring kit, and he probably knows the properties of the rings therein (like whether they are fuel compatible) and where he sourced the kit. I have a similar kit, but mine was a gift and I don't know much about it - I imagine it is primarily intended for hydraulic applications. If the o-ring is part of the inlet valve, it would be in regular carn kits and available at the dealer, right? When I needed an o-ring for the enrichener system on the DR350 (a really oddball unit that is actually part of the float assembly) I just found a SAE one I liked the id of and sanded down the od - but that would be a pain on four carbs, I admit, and the inlet system is fussy.
