Cast alloy angle tyre valves that replace the standard wheel valve. 
They offer the following benifits:
They are fixed to the rim with a lock nut, therefore they can not bend nor be expelled from the rim
The angled shape reduces the effect of centrifugal force, which tends to fling the valve core outwards in a conventional valve, leading to loss of pressure in the tyre
No rubber to perish.
They completely solve the problem of access for inflation
 
They are used in British Superbike so are up to the job on a FJR. I have been using them on my own bike and they work fine and make checking tyre pressures a breeze. Once fitted they should last a lifetime as there is no rubber to perish. This will negate the fact that they cost £10 each. If you're having a tyre fitted at the club then I will fit them Free Of Charge. Your local tyre fitter can fit them easily if you ask him nicely.