Ok some background.
I bought a 1990 Seadoo SP 2-3 years ago. Ran it for a season, and blew the motor due to friends sinking it and from a bad o-ring.
We've replace the crank, pistons, cases, head, head cover, and rotary valve.
The situation with the rotary valve is that the new one has the identical shape to the old one (same degrees), but the teeth that are cut into the valve plate are offset by one tooth, so when we put the rotary valve on the motor with front piston set at top dead center (TDC), the leading edge of the valve did not align with the alignment mark which is cast into the crank case. Currently the leading edge is one tooth clockwise from the mark. The old rotary valve lined up perfectly. When we flipped the rotary valve over and tried it, it was even further from the mark, clockwise. So it's currently set up with the intake port timing one tooth advanced. This may have been an enhancement that went into the late model 90 seadoos, since the new cases have Spring 1990 date on them vs. the Fall of 1989 date that was on the old cases.
Any idea as whether we should advance or retard timing by a tooth?
I bought a 1990 Seadoo SP 2-3 years ago. Ran it for a season, and blew the motor due to friends sinking it and from a bad o-ring.
We've replace the crank, pistons, cases, head, head cover, and rotary valve.
The situation with the rotary valve is that the new one has the identical shape to the old one (same degrees), but the teeth that are cut into the valve plate are offset by one tooth, so when we put the rotary valve on the motor with front piston set at top dead center (TDC), the leading edge of the valve did not align with the alignment mark which is cast into the crank case. Currently the leading edge is one tooth clockwise from the mark. The old rotary valve lined up perfectly. When we flipped the rotary valve over and tried it, it was even further from the mark, clockwise. So it's currently set up with the intake port timing one tooth advanced. This may have been an enhancement that went into the late model 90 seadoos, since the new cases have Spring 1990 date on them vs. the Fall of 1989 date that was on the old cases.
Any idea as whether we should advance or retard timing by a tooth?
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