If you can't find the original specs ,I would just set the clearance the same as a Honda motor .006 thou intake and .008 thou exhaust..
I'd turn the motor over until one valve is fully open ( intake open) then check and adjust the other valve ( exhaust clearance check adjust) then turn motor so exhaust valve is fully open and adjust intake valve.
You adjust the valves as above, otherwise you can mess up the adjustment when the compression release works on a valve at top dead centre.
