here is some i like
"you don't stop riding because you get old, you get old because you stopped ring"
"when in doubt throttle out" got that one covering the warning sticker on the throttle side hand guard.
"you lift you lose"
"Harley Davidson, the most enchant way to convert gas into noise with out the side effects of horse power"
" pin it to win it"
"some fear, because no fear means your not pushing it far enough"
"a bad day riding (or racing) is better than a god day at work"