Veteran W&P valve timing

[huw.parsons]

Just measured the valve timing on my 1912 Ariel TT

Inlet opens 1/16" or 10 degrees before TDC
Inlet closes 1/4" or 30 degrees after BDC
EX opens 7/8" or 70 degrees before BDC
EX closes 1/8" or 15 degrees after TDC

Valve lift 5/16" inlet and 3/16" exhaust

clearances set to 1/64" or 16 thou or 'the thickness of a calling card' as it says in the owners guide!
I tried a more normal 6 thou as well but it made very little difference.

My only observation is that the exhaust valve opens really early; perhaps thats why the bike sounds like a steam train
crossed with a dumper truck.

These figures point to the cam profiles being post 1913 and match the figures given for the rest of the engines natural
life up to 1926. it certainly pulls well both at slow and fast revs which is just as well having no gearbox or clutch.

I'm sure someone asked me for timing info a few months ago; hope this helps..

Cheers

Huw