Poor performance

[Gary pope]

Ok, I got it started finally. One issue I’m having is when it is idling it idles pretty rough and backfired and when it back fires I can see the fire down in the carburetor....if I give it throttle it bogs down before it gets going. Any ideas on what to do? I did rebuild the motor, adjust the rotary valve timing, and rebuilt the carburetor...

 

[mikidymac]

Timing is wrong if it backfires out the carbs.

 

[Gary pope]

Isn’t tgere a way to adjust it while it’s running, like a car?

 

[mikidymac]

Absolutely not.
There is ignition timing that is controlled by the stator and you just align the marks on the cases and stator.
The intake timing is by the rotary valve.

 

[Gary pope]

I made sure I aligned the mark on the stator and case...

 

[Gary pope]

So you’re saying somethings going on in the rotary valve timing then?

 

[mikidymac]

That’s my guess.

Did you use a dial indicator to make sure the MAG piston was at TDC?
Did you use a degree wheel to mark the cases per the manual?

 

[Gary pope]

I used a screwdriver and brought it up to tdc and used a degree wheel yeah.
When I did this I noticed that my marks corresponded with the last marks someone made on it.

 

[mikidymac]

Only other thing I can think of is a leaking needle and seat dribbling and flooding it.

I do know the factory scribe marks on the cases under the rotary valve are not correct for aligning it if those are the marks you saw.

 

[Gary pope]

If you are referring to the little tab that is near the top, no I did not go by that I put the degree wheel at the bottom of the magneto side opening and lined it up with the 0° Mark on the degree wheel, went counter clockwise backwards to the degree for a 97 Sea-Doo GTS 720, which I think is 142 degrees And marked it there, that is where I aligned the rotary valve, on their mark. I could have sworn that I did everything properly

 

[Gary pope]

I’ll head out there tomorrow and take the rotary valve back a park, bring it up to top dead center in remarket and I’ll take pictures and show you where it is at

 

[Gary pope]

Oh my God I can’t believe I did this, I went back out there this morning and double checked the mixture screws and bolts screws were all the way in still, I backed Out the I believe it’s the low-speed mixture, the one that doesn’t have the One and a half turns no more backfire runs good now. I can’t believe I missed that

 

[Gary pope]

Can anybody clear up this vague area that I have encountered with regards to the pop off pressure. This boat is a 95 speedster with the twin 657X motors in it in the manual calls for the pop off pressure to be between I think it was 16 and 21 PSI’s. Now I have read online that it should be much higher than that does anybody have any input on this? I need some help here

 

[Gary pope]

Anyone?

 

[mikidymac]

When in doubt go by the manual.