54 divided by 16 equals 3.38 to one
51 divided by 14 equals 3.64 to one
take the size of your front sprocket and mutply by 3.64 and you get rear sprocket size but you will be way off probably.

16 times 3.64 equals 58.24 teeth you arent taking the trans ratio and primary ratio into account. In second gear that is probably about 3.5 to run (3.64 times 3.5) is 12.88 to one way too low for that track. Get a manual for your motor. Look in specs. Get primary gear ratio and second gear ratio multiply primary by second gear times sprocket ratio get you your final ratio. We run about 12 to one at little salem.