I like to coat the feeler guage with a little bit of oil, and tighten until you just start to feel resistance while pulling it out. If you're dealing with small clearances, .002-.004, you should feel the resistance while pulling it out and the feeler guage should try to buckle slightly if you push it back in.
2014 CRA Senior II and Buckeye Series champ
2012 CRA Senior II champ
2011 CRA Senior II and Buckeye series Harescramble Champion
2009 CRA Senior II and Buckeye series champ.
2007 CRA Senior II, and Buckeye series Harescramble Champ.
2003 Lonestar 250R
2001 Lonestar 250R.....now a 310
1986 TRX250R (restored to new)
1986 TRX250R (still in pieces)