You really dont want to spin a valve to lap it,it should be oscillated back and forth,so that it seats properly. I use a simple suction-cup tool,but ZIM also makes a hand-crank one,that does the oscillating for you,you just crank it in one direction. Another handy tool thats cheap is the Stens or ZIM Small-Engine Valve Refacer,its about $35 and works great on these valves,if you have one that the face is beat up a little. Hope this helps.
