9. Now install the left case onto the right case, guiding the right end of the crankshaft through the right main bearing. Gently tap the left case with a plastic or rawhide mallet until it mates evenly with the right case.
10. Turn the cases around so that the magneto side is facing you, and install five or six of the engine case screws. Tighten them snugly, but not firmly.
11. To calculate the crankshaft end play, shift the crankshaft to the left by gently tapping on its right end with a plastic or rawhide mallet. Using the depth gauge end of the vernier caliper, measure the distance from the right end of the crankshaft to the inner race of the right main bearing. Fig. 85 illustrates this. Write down that measurement. Then, gently tap the left end of the crankshaft with the mallet, moving the crank to the right. Again measure the distance from the right end of the crank to the inner race of the right main bearing, being careful to take the measurement at the same place as the first one. Subtract the smaller of the two figures from the larger. The difference represents the end play of the crankshaft.
12. The correct crankshaft end play is .004" to .008". If the end play of the shaft you are measuring is not within these tolerances, add or subtract shims from either side until the correct measurement is obtained. Crankshaft
shims are available in thicknesses of .004" (No. 991-139-11), .008" (No. 991-139-IV) and .020" (No. 991-139-X).
13. If you find it necessary to remove or add a large number of shims, or shims totaling more than .008", do not do it all on one side. If possible, add or subtract an equal number of shims from both sides. This tends to keep the crankshaft better centered in the cases and makes the final alignment check a little easier.
14. After you have arrived at the correct crankshaft end play, the final step is to align it properly so the connecting rod runs equidistant from both flywheels.
15. To do this, leave the cases bolted together after attaining the
proper crankshaft end play. Locate the piston you are going to install
in the cylinder. If it is dirty, clean it and remove the rings from it.
Put the wrist pin bearing into the connecting rod and then