B33 valve dimension

[Derek996]

I am restoring a ZB32GS cylinder head to operational condition. I have managed to buy the correct new inlet valve but been stumped with getting an exhaust valve. I am therefore modifying a DBD 34 exhaust valve to fit. The head is the right diameter, the stem is the correct 8.9mm diameter but it is too long and with a semicircular groove for the collets. My intention is to shorten it to the correct length and turn down the stem ago accept the square bead collets. Can someone who has a B33 inlet valve or a B31 exhaust valve measure the valve stem diameter across the base of the collet cutout for me?
I'm also struggling to find valve collets for the exhaust, part number 15-1525, used on the B31 exhaust and both valves of the B33/M33. See my ad in the "Wanted" section.

[martinh10]

The reduced diameter for collet on a spare (used) B31 exhaust valve I have measures ".299 dia. - so probably manufactured to ".300?

[Derek996]

Thanks Martin. That helps me a lot. For reference, the inlet has a reduced diameter of 0.250"