1985 Ski-Doo snowmobile Service Manual, Page 143Get this manual

Section 02 ENGINE Sub-section 07 (503 ENGINE TYPE)

NOTE: Spare parts pistons and cylinders are identified with green or red dot, It IS Important to match the piston with the cylinder of the same color
To minimize the effect of acceleration forces on circlip, install each circlip so the Clrclip break IS at o'clock as illustratedRemove any burrs from piston caused through circiip installation using very fine emery cloth

Piston notch

A017002002

Or use exhaust manifold to align cylinders

18,19,20, Noise dampers
For proper position of noise dampers, refer to the following illustrations

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives