That's how I've been doing valve adjustment on motorcycles. It verifies that you got it at close as possible to the correct clearance!

When you do work like this make sure you give yourself plenty of time to do the job and don't rush! Always double check yourself!

 

And always rotate the engine by hand at least once after setting the valves. This will put tension on the rocker arm and valves. Then go back an recheck the lash to make sure none have loosened up. And if you really wanted to be prudent drive like normal for a week or two and go back and recheck the valves.

 

What you should buy to be more accurate is a "step gauge" or "go-no-go feeler gauge". You can buy them at most reputable shops. They are more accurate than using the 2 different size feeler gauges.

 

Can anybody tell me what size allen wrench this takes?

 

Can't remember exact size but it is slightly less than 1/4 inch, and most likely in metric also. The open end wrench required is a 9/16 inch, but a 14mm works also. Check out my gallery for more valve adjustment pictures.