There are 28 grams per ounce and 16 ounces per pound.
So if you multiply 28 grams x 16 you will get 448 grams per pound.
448 grams x 50=22400 grams in 50 pounds
It depends on the size cubic centimeters or cubic inch of each motor.
The one that has the most cc/ci's will burn the most gas.