You may not be too lean. The plug should self-clean. You must cut the threads off the plug and check the width of the black ring on the insulator and jet accordingly to truely approach maximized performance.
Tan, after a plug chop, is not too lean. Its good enough for some people, and too rich for others.
If you want to ride max performance, then adjustment to weather will be typical.
Naturally, any grey on the cathode is very bad and means you are a couple steps too lean and will grenade it.