1970-1979 Ski-Doo Snowmobiles Service Manual, Page 57Get this manual
CHAPTER FOUR
Ski-Doo snowmobiles are equipped with single and twin cylinder 2-cycle enginesThe high performance twin cylinder engines are equipped with rotary valves, all other engines use piston-portingAll engines have ball or roller main crankshaft bearings and needle bearings on the lower and upper bearings of the connecting rodsThis chapter includes removal and repair procedures for most engine componentsHowever, due to the special tools and expertise required, all crankshaft assembly inspection and alignment should be performed by an authorized dealer or competent machine shopSome procedures in this chapter require the use of special toolsIn all cases the special tools are illustrated and in many cases can be easily fabricated or substituted by well-equipped home mechanicHowever, each snowmobile owner must be honest with himself about his own supply of tools and expertise and avoid repair procedures that are not within his capabilitiesIt is often cheaper and easier in the long run to remove the engine and take it to an authorized dealer for required service and repair than to risk expensive damage if you do not have the proper tools and facilities for the necessary work