I so agree with you lawnmowerman concerning heating valves.
I have used them on many bikes (except my A for some reason, as her pull-me-push-mes will insist on working). Even on quite 'posh' ones.
The nasty plastic strip can be hoicked off and slung, and the black paint scraped off to reveal dull grey on the lever. A small bit of stainless or polished ali strip, trimmed to fit the recess where the plastic bit was, can make them look half-decent even. For the square root of diddly-squat £$€, they're pretty unbeatable. Not right, of course not, but certainly fuel-proof, fool-proof and long-lasting, with an easy action.
Adaptors up and down the BSP sizings from 1/8 to 3/8 are easy to get as Lee said, so they really are usable on almost anything - but . . . only if functionality is the primary objective.
My little bag of Ewart and other corks just sits . . . and sits. Long may it remain unraided.
(The larger 10mm valves make good oil line taps too . . . yeah, I know . . . which are also quite easy to rig up to disable the ignition when the valve is closed. Got 4 of them - but not on the A again, as she hasn't dribbled since visiting the urologist.)