1986 Ski-Doo Factory Shop Manual, Page 206Get this manual
Section 02 ENGINE Sub-section 09 (537 ENGINE TYPE)
- Position the rotary valve on gear in such way that its closing edge will be as close as possible to the bottom of the magneto side inlet port, and its opening edge in line with the mark (ridge) on the upper left side of the rotary valve cover
ENGINE TYPE
TIMING MARKS
opening closing
532 For example; 132 opening 520 closing Using angle findermark crankcase at 132 from bottom edge of magneto side inlet port132 520