Part A will cover the disassembly, repair, and reassembly of the engine and its components. The instructions are sequenced so that they cover a complete engine repair. However, if you desire to service only one particular component of the engine, and it does not require complete disassembly of the engine, refer to the chapter and section that pertains to that component.
It is advisable to clean the entire motorcycle before removing the engine. It is easier to work on a clean motorcycle, and always results in a more efficient, satisfying repair job.
Locate or grind large screwdrivers so that their tips will fit the OSSA engine screws perfectly. Failure to do this will result in damage to the screw heads and just make the chore of their removal and replacement more difficult. Most cycle shops sell impact screwdriver kits which allow you to loosen and tighten engine screws efficiently and without damage to them.



Section 1:

Removing The Cylinder And Piston

1. Clean the exterior of the engine carefully, and if it is going to be completely disassembled, drain the oil from the gearbox by removing the 17mm plug from the bottom side of the engine cases. After removing the plug, slowly tilt the engine from right to left and from front to back. This will allow the oil to reach the drain hole from behind the several obstructions which would normally block its flow. After the oil has been allowed to drain from the engine, check the condition of the drain plug gasket and, replace it with a new one if needed. Reinstall the drain plug and tighten it.
2. Remove the spark plug.

FIG. 1

3. From the top of the cylinder head, viewing the front of the head as being 12 o'clock on the face of a clock, use a 12mm socket to loosen the four cylinder head nuts 1/4 turn each in the following sequence:

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