1983 Ski-Doo Shop Manual, Page 75Get this manual

SECTION 02 ENGINE
SUB-SECTION 04 (464 ENGINE TYPE)

For example: 150 opening 49 closing Using angle finder, mark crankcase at 150 from bottom edge of magneto side inlet port
To correctly install the rotary valve disc proceed as follows:

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