Some of the smaller Yamies run at 100:1. Oil injected motors run leaner then that at an idle. Is the motor broke in? If the manuel says 100:1, I'd say it would be OK, but I think I would run a synthetic, such as Synergyn, Pennsoil, or Amsoil.
BTW if you're still scared of 100:1, go richer, the synthetics don't seem to smoke as much.