1996 xp big after rebuild.

[Nmskiguy]

I have a 1996 Sea-Doo XP 787

It has a new motor, compression is good I just rebuilt, carburetors, new diaphragms, pump rebuild, O-rings and gaskets pop off is at 30 psi, the ski will only start with starting fluid and will not start with the intake box on. Some issues that I’ve noticed, and I could probably use some help as I’ve gone through the manual.

If you get it to start, it sounds like it’s got a very rich bog, it idles not a smooth idle, but it will not ramp up in RPM, you give it any throttle it’ll increase is slight bit, and then it’ll just sit there no matter how much throttle you give it after that.
I’ve pulled the carburetors off at least three times and gone through them at least three times. One thing I noticed on the twin carb is that it seems to not push much excess fuel out of the mag side carb to the return. It pushes fuel to the PTO carb and the PTO carb pushes a full hose of fuel to the return but the mag side pushes very little to none at all.

 

[Nmskiguy]

Here is a video of it running.

 

[mikidymac]

Did you rebuild the carbs with all new Genuine Mikuni parts and follow the Carb Rebuild Thread to the letter?

 

[Nmskiguy]

Yes, I bought Mikuni carb kits.

I followed the book, and went through the whole thing. I thought there might be something I missing, or some thing I forgot. No matter what I do to the carburetors it always does the same thing

 

[mikidymac]

Did you install new needles and seats?
Did you keep the stock pop'off springs?
IF you think the carbs are good then run a hose directly from the tank supply to the carbs to eliminate the fuel filter and on/off valve as issues.
Did you get the rotary valve timing correct?
Did you check rotary valve clearance?

Also starting fluid is not good for 2-strokes.

 

[Nmskiguy]

Did not check clearance will do and check back in

 

[Grim]

Have you verified you don't have a vacuum on your gas tank?

 

[Nmskiguy]

Ok rebuilt carbs again, checked rotary valve timing, new orings, seats needles, pulse pump, diaphragms, same scenario

 

[Nmskiguy]

Did you install new needles and seats?
Did you keep the stock pop'off springs?
IF you think the carbs are good then run a hose directly from the tank supply to the carbs to eliminate the fuel filter and on/off valve as issues.
Did you get the rotary valve timing correct?
Did you check rotary valve clearance?

Also starting fluid is not good for 2-strokes.

OK so everything is now new original Mikuni, new seats, needles, fuel lines, new fuel, selector, etc. rotary valve timing was double checked again. Everything is good to go. In that regard it actually fires up way better. It will pretty much instantly fire up now, but the plugs even though I just put new ones in I ran it for about 10 seconds and it still bogs when you give it gas and it will not rip up at all same as the video previously .

Brand new plug only rang for about 10 seconds in this picture

Could it be electrical and if so, where should I start?

 

[burtshaver2021]

Looks lean to me, what are your low and high set at? Have you tried running a line direct from the tank to the carb? Not that I think compression is your problem but curious what it is? I know you answered this before but since you rebuilt the carb again what is it popping off at?

 

[Nmskiguy]

Looks lean to me, what are your low and high set at? Have you tried running a line direct from the tank to the carb? Not that I think compression is your problem but curious what it is? I know you answered this before but since you rebuilt the carb again what is it popping off at?

30lbs pop off.
It’s covered in oil and gas
High set at 0
Low set at 1 turn

But good news got it figured out…happed to be an electric issue, spark looked weak, looked in box and grounds were all corroded cleaned and bam big nice spark and bam runs great …so idk

 

[burtshaver2021]

Right on,