First off you should have the factory manual if you are this deep into the motor. Actually the ideal combo is Hondas general service manual, the RC51 factory manual and maybe a aftermarket manual to translate the "Honda Way" for those unfamiliar. That being said, I'm here to help. Main journal code ( numbers 1,2 or 3) is found on the crank weight. the crankcase bearing codes are on the left side of the upper crankcase. Will be an A,B or C. Refer to chart on page 12-5 for selection of yellow, green, brown, black or blue bearing. After you clean the bearing area, use Plastiguage to check the oil clearance. Main journal clearance is .0008" to .0015".