1972 Ski-Doo Shop Manual, Page 149Get this manual
lWO CYLINDER
Engine Types 343401 II 640!
NOTE: The following step is not applicable to 440 engines because of the crankshaft being held on P.T.Oside with bearing thereby controlling crankshaft tolerance(d) Insert screwdriver blade between magneto crankshaft blade and crankcase and push the crankshaft assembly toward P.T.Oside of crankcaseAny free play between retaining disk and the leading edge of the bearing located between the retainer disk and magneto crankshaft blades, minus tolerance of .006 to .016 inch is the distance to be covered with shimsThe shims must be equally positioned between magneto crankshaft blade and bearing andP.T.Ocrankshaft and bearing (fig2-3-23)23-22A