In this Post I'm going to Show you how To install and time A ski-doo motor That uses a rotary valve timing system.

TOOLS YOU WILL NEED - Dial Indicator AND Degree Wheel

STEP 1: First what you'll want to do is find the Top Dead Center(TDC) for the Right(MAG) side cylinder, Remove both spark plugs. Screw an extension onto the dial indicator and insert the Dial indicator into the adapter, screw the Dial indicator into the cylinder head on the MAG side(do not lock the Dial indicator into the adapter at this time)


STEP 2: rotate The primary clutch until the dial indicator rises all the way in its Holder(piston is approaching TDC) Then slide the indicator far enough into the holder to obtain a reading. lightly tighten the set screw on the dial indicator adaptor to secure the dial gauge.



STEP 3: rotate the primary clutch until the dial on the gauge stops and reverses direction. This is Top Dead Center(TDC) zero the dial gauge by aligning the zero with the indicator needle --- tighten the set srew on the dial indicator adaptor securely

STEP 4: now that your motor Is at TDC you can install the degree wheel on the rotary valve shaft with 360-0 degree mark aligned with the lower(BOTTOM) edge of the right(MAG) side Inlet port. Now mark crankcase as shown in picture, at this location, mark in degrees As "___ Opening BTDC" EXAMPLE ONLY --> "145 Opening BTDC" <--- EXAMPLE ONLY(see picture Below)


STEP 5: With The engine still at TDC reposition the degree wheel on the rotary valve shaft with the 360-0 mark Aligned with the TOP edge of the Right(MAG) side Inlet port, Mark the Crankcase as Show in picture. mark it in Degree as well only this Time "__Closing ATDC"(see Picture below)


STEP 6: Now you can position the rotary valve on the gear so its edges align with both mark made in Step 4 and 5.

NOTE !!!!!! :The rotary valve is asymmetrical. if he marks do not align, turn the valve over to determine which position provides the more accurate timing.


Now that your rotary valve timing is set you can now put the O ring in the cover(back of oil-pump) and install the cover/pump over the rotary valve just as you did when you removed it.


Below i have Made a Chart table for All the models from 90 to 95, IM ONLY HUMAN AND I MAY HAVE MADE A MISTAKE!(however i believe it Is perfect)

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Ran out of time to add the Chart So here it is Now.

ROTARY VALVE TIMING (all in degrees)

1990 ------------------------ OPEING BTDC -----------CLOSING ATDC

467 engine models ------------ 132 -------------52
563 engine models ------------ 117 -------------52
563(formula pluss 500) ------- 134 -------------68
583 engine models ------------ 140 -------------68
1991

468 formula mx X --------------143 -------------66
other 469 engines ------------ 132 -------------52
546 formula plus X ------------134 -------------69
other 563 engines ------------ 137 -------------61
636 formula mach 1 X---------146 -----------75

other 643 engine models -------142 --------- 70
1992

467 engine models --------- 132 --------- 52
582 engine models --------- 129.5 --------- 69.5
583 formula plus X --------- 141.5 --------- 69.5
643 engine models --------- 144 --------- 72
670 mach 1 X --------- 146 --------- 75
1993

467 engine models --------- 132 --------- 52
582 engine models --------- 129.5 --------- 69.5
583 plus X --------- 141.5 --------- 69.5
670 engine models --------- 146 --------- 75
1994

467 MXZ X --------- 145 --------- 65
other 467 engines --------- 132 --------- 52
582 engine models --------- 134 --------- 65
583HAC engines --------- 132 --------- 52
other 583 engines --------- 134 --------65
670 engine models --------- 144 --------- 72
1995

454 MXZ --------- 145.6 --------- 64
467 engine models --------- 132 --------- 52
582 engine models --------- 129.5 --------- 69.5
583HAC engines -------- 134 --------- 65
Other 583 engines --------- 140 --------- 71
670 mach 1 Model --------- 145 --------- 76
Other 670 Engines --------- 144 --------- 72

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Here Is some More helpful info I found Floating around


IF You Do Not Have A Degree Wheel. Here Is A Print Able One Click here


Example photo's

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