There are Two ways to do it,
First way can be done at any time by simply fitting a 4/5mm bearing inside the allen head bolt shown here
http://www.hallbergs.net/kx500/images/picture11.jpg Second way only can be done with the topend removed {the way i do it}
This way i put the kipps valves on differant grove on the valve rod/ but modify the stop on rod
This way has the advantage It will keep the kipps rod in original position /angle
The black ARROW point to the way i modify the stop with a 5mm width nut
valves in closed position
i later modified this valve for better flow but this is correct position for stock valve
Not great flow from pre89 valves in closed position that why i modify one