Procedure for Rotary Valve Timing.

This procedure describes the proper way to install a stock OEM Sea Doo rotary valve. If you have an aftermarket one, use the manufacturers instructions for installation.
In order to place the Rotary Valve in the proper position on the Rotary Shaft, you will need to have a special degree wheel made by Sea Doo (295000007) or you can make one yourself. If you want to make one, follow the procedure below. Also note that there is usually a mark lightly scribed in the rotary surface which will save you some trouble. If not, you'll have to mark the rotary surface.

To make a wheel, first, you need to know the BTDC Timing Opening for your year/model. To find this, check the specs below for the proper BTDC opening. If you have a different engine than those listed, contact your dealer for opening specs.
You’ll need a piece of cardboard from something like a cereal box. Start by drawing a line horizontally about 6" long. Then mark a center point in the middle of the line. Next, use a protractor (centered on the center point) and measuring counterclockwise from zero (zero being the right end of the line), mark the BTDC TIMING OPENING degrees from the chart below.
Finally, using a compass mark inner and outer circles. The inner circle is 1.25" and the outer circle is 4.75". Cut out the inner and outer and you'll be left with a donut with zero point and BTDC Opening Degree point marked.

YEAR MODEL VALVE OPENING TIMING OPENING (BTDC) TIMING CLOSING (ATDC)
1988
SP
132
132
52
1989
SP
132
132
52
1990
SP
132
132
52
GT
132
132
52
1991
SP
147
115
80
XP
132
115
65
GT
132
115
65
1992
SP
147
115
80
XP
147
130
65
GTS
147
115
80
GTX
147
130
65
1993
SP
147
115
80
SPX
147
130
65
SPI
147
115
80
XP
147
130
65
GTS
147
115
80
GTX
147
130
65
1994
SP
147
130
65
SPX
147
130
65
SPI
147
130
65
XP (5854)
159
149
65
XP (5855)
147
130
65
GTS
147
130
65
SP
147
130
65
1995
SP
147
130
65
SPX
159
147
65
SPI
147
130
65
XP 800
159
147
65
XP
159
147
65
GTS
147
130
65
GTX
159
147
65
HX
159
147
65
1996
SP
147
130
65
SPX
159
147
65.5
SPI
147
130
65
XP
159
146.5
64
GSX
159
146.5
64
GTS
147
130
65
GTI
159
147
65.5
GTX
159
146.5
64
HX
159
147
65.5
1997
SP
132
134
51.5
SPX
159
146.5
64
GS
159
147
65.5
GSI
159
147
65.5
GSX
159
146.5
64
GTS
159
147
65.5
GTI
159
147
65.5
GTX
159
146.5
64
HX
159
147
65.5
XP
159
146.5
64
1998
SPX
159
147
63.5
GS
159
147
65.5
GTS
159
147
65.5
GTI
159
147
65.5
GTX RFI
159
147
63.5
1999
SPX
159
147
63.5
GS
159
147
65.5
GSX RFI
159
147
63.5
GTS
159
147
65.5
GTI
159
147
65.5
GTX RFI
159
147
63.5
2000
GS
159
147
65.5
GSX RFI
159
147
63.5
GTS INTER.
159
147
65.5
GTI
159
147
65.5
GTX RFI
159
147
63.5
2001
GS
159
147
65.5
GSX RFI
159
147
63.5
GTS
159
147
65.5
GTI
159
147
65.5
GTX RFI
159
147
63.5
2002
GTI
159
147
65.5
GTI LE
159
147
65.5
GTX RFI
159
147
63.5

Tools needed:

Procedure:

  1. Bring the engine to TDC (Top Dead Center) on the front (magneto end) cylinder. Do this by using a dial indicator on the front piston or you can use a screwdriver in the front cylinder (not as accurate) if the head is on the engine. Rotate the engine back and forth until you are sure you have the piston at TDC.

  2. Install the Degree Wheel on the rotary shaft and align zero mark with the bottom of the front port. The opening BTDC degree mark should be on top pointing towards the rear cylinder. Lightly scribe a mark in the rotary surface at the BTDC degree mark.

  3. Remove the wheel and install the rotary valve with the gap in the valve exposing the front port and the top edge hitting the line you marked. The rotary valve is asymmetrical, so if you can't get it to align, flip it over. That should get you in the ballpark. If you have any questions, e-mail me.


(picture above using 130 degree BTDC as an example)

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