Rotary Valve Timing Expert Help

[mikidymac]

I have done a few of these before and need expert help. Stock 720 and 159 degree wheel. My timing marks are correct and dial indacator says TDC. With my damaged OEM valve everything lines up correctly on one side and if I flip it over it is way off. When I install my new WSM one it is off about half a tooth and it does not change if you flip it over so I need to know if this is a problem being off this much?

If the error is ok is it better to be advanced or retarded?

BTW: I called WSM and the tech was a complete jerk and told me I was wrong there was no way the valve could be different when flipped and the OEM one must be magic bucaust there's was correct and had to be the same no matter what side was up.

 

[lbustin]

I can't answer all those questions, I'll let the ones with more knowledge go for that. But, I saw this video linked in another post and it made me realize that I had put my rotary valve on complete bass ackwards. I swapped it around and my motor fired right up. Maybe you can glean some of the info you need from it.

http://www.youtube.com/watch?v=ULL5gfQs_UA

 

[mikidymac]

Thanks for the input but I think my issue is the valve not me although I was wrong one time but that was a long time ago LOL.

 

[El Toro 33809]

I have installed the rotary valve plate a few times in our 720 engines. I believe the plate is made to be offset..... That way you can get it close to perfect. You can't put it on upside down or inside out. I have always seen which way is the best "fit" to have it timed correctly. One was always much closer to exactthen the other way.

The latest engine I installed one on had a mark on the case that would show where the opening should line up. All I had to do was find TDC for the correct piston (front if I remember correctly), and then align the plate. No wheel necessary.

 

[mikidymac]

You are correct El Toro, my factory valve is aligned perfectly but has a chunk missing from it. The issue is that when I put the WSM replacement valve on it is off and unlike the OEM valve the WSM valve does not change if flipped over, the OEM valve is asymetrical to allow the minor adjustment and the WSM is symetrical not allowing adjustment. The WSM valve seems to be stamped in the middle of the OEM range so you either have to set it one tooth advanced or one tooth retarded and can not get it perfect like the OEM. The WSM is a poorly made part and falsly advertised as "OEM" in my opinion. I just need to know if it is a performance issue and if I should install it advanced, retarded or not at all.

 

[El Toro 33809]

I follow you now...... I am not familiar with the WSM plate. I have only used OEM or ones purchased from SBT and they are asymetrical as mentioned. I am not sure what would be best..... advanced or retarded. I am sure it would be a performance issue. Someone else will probably chime in with an answer for you, unless you go with your third option..... Not at all and get a different one.

You did a very good job of clarifying and putting into words what I was trying to say.

 

[griz400]

When installing a Sea-Doo 587, 657, 657X, 717, 787 or 787 RFI engine, your rotary valve must be timed. To do so requires a timing degree wheel, and the degree specification for your particular engine:

’90-‘93 SP, ’91 GT, ’91 XP, ’93 SPi
115

’92 GTX, ’92 XP
129

’88, ’89, ‘94-96 SP, '94+ SPi, ’90 GT, ‘93-'94 SPX, ‘93-'94 GTX, ’93 XP, '92-'96 GTS
130

‘95+ SPX, ‘94+ XP, ‘95+ GTX, '95+ HX, '96+ GTi, '97+ GTS, 1997+ GS, 1997 GSX, '97 SP
147

Place a screwdriver, pen, etc., or use a TDC gauge in the front (MAG) cylinder through the spark plug hole. Turn the crankshaft to find Top Dead Center of this piston.




Place a timing degree wheel over the rotary valve gear, aligning the 360° mark at the bottom of the front (MAG) intake port.


Find the timing spec for your particular year and model. Using the inside track of numbers, make a mark on the case corresponding to the timing spec for your engine. This will be somewhere around 11 or 12 o'clock on the case. NOTE: do not automatically use the notch on the case to time by - you NEED to make sure it's timed correctly.


Align the rotary valve as shown so that the port is open, and the edge of the valve matches as precisely as possible with the mark. NOTE: the valve is asymmetrical. Flip it around to find the closest match.



******** note - values are plus or minus 5 degrees, as per seadoo manuals ****** there is always a little play in rotary valve and in rotary gear ******

 

[mikidymac]

I completely understand the process and like I said the OEM valve is within specs at about 4 degrees off but the best the WSM one will get is 8 degrees off. This is using a dial indicator and degree wheel so this is as accurate as it gets.

Unless the experts have a better idea it looks like WSM is a piece of sh@#t and I wasted my money.

 

[Robj]

That is easy, the spec calls for +/- 5 degrees, if it is outside that spec then send it back. 8 degrees is too much IMO.

 

[skewba98z28]

I found out if you get one timed close, but not good enough it will run out of the water and not run in the water. I bought a 93 XP that the owner rebuilt the motor, but had the valve about 20 degrees out of time!

 

[mikidymac]

Thanks everybody that is what I thought and just wanted others to confirm it. I have been working with Dan at FullBore Online as he supplied the WSM valve and he said the same thing and offered to refund me for the valve so I will be ordering the factory valve today. Dan's customer service is first rate.