Carb trouble

[JasonD]

Having trouble getting my 92 (91?) XP running right and hope I can get some help. So this has been a build and the whole seadoo motor and pump are mounted in a 14' jon boat. I was told when I got the ski that it was a '92 but after going through it I found it has a 132 degree rotary valve in it that is what is specified in a '91. Anyway to tell if this is the right valve for this motor without the hull ID number to verify? I halfway had this thing running when I first built it, rough through the midrange but once through the mid I could run 35 mph in the boat. I then put new jets in the carb and set the pop off pressure at 25psi with the black 80g springs. Now I can't hardly touch the throttle without it falling out. Have low speed screw anywhere from 1 turn out to 2 1/2 turns out and couldn't get it going right. Idles real smooth at 1 1/4 turns out but won't go anywhere. Did find a sweet spot at one time today where it took off hard then fell flat on it face and died, tried tweaking low speed screw but could never get it back.

Old jets I took out were halfway closed off with build up.

Also the compression is low, 125ish on each on my old gauge, how would this affect any of the carb settings?

What actually builds the pressure for the pop off in the carb? If I had a air leak in the fuel tank somewhere with this be prohibitive?

I tried putting in the 65g shiney silver springs I just got from SBT but they held higher psi than the black, 30 with silver and 25 with black.

To clarify:
Pop off 25 psi with black 80g spring.
Main jet: 107.5
Pilot jet: Believe I have the 65 in it but looking at the chart now the '91 has 65 and '92 has 62.5. Throwing my memory...
Compression: 125 both cylinders
Needle and seat: All new 2.0

Sorry for long post, trying to get any beneficial info out I can.

 

[Minnetonka4me]

Easy way to distinguish between the 91 and 92....91 was a yellow motor, 92 was a white motor. The yellow motor has a mag housing that is as tall as the motor, and has the coil inside, where the white motor is just a bit bigger than the bottom end and has the coil in the grey box.

Dont buy carb parts...hell I dont buy anything from SBT. junk. I carry only genuine carb parts in stock.

Let me know what motor we are dealing with and I will help further.

 

[JasonD]

Thank you, I thought I had posted but of course I didn't, it is the yellow motor. It was sold to me as a '92 but the more I dug it looked like it was in fact a '91, the guy just honestly didn't know what he had. That's great to know about your mikuni parts, they were the easiest source to find for me with everything I needed.

 

[Minnetonka4me]

No problem. It was out of a XP if it had dual carbs.

If I had a air leak in the fuel tank somewhere with this be prohibitive?

absolutely...the fuel water separator (oring) and your fuel line selector can suck in air bubbles causing it to run like crap.

 

[JasonD]

Do you think 25 psi is too high for the compression I have at 125 psi? Should be 150 psi

 

[Mekanix]

Do you trust your gauge ?

 

[Minnetonka4me]

I dont think it would affect it....but its a good question.

 

[JasonD]

No clue on accuracy of gauge and I have never verified it. It was one my father in law had in his toolbox that was hardly used.

 

[RodInEscondido]

try another compression tester, these things can lead you astray