Can someone verify these stock carb jet sizes?

[Krispy]

I am currently diagnosing a 97 GSX that bogs off idle.

I am trying to delete the accel pump to see if it is the cause problem.

I have looked in my 97 GSX and my 96 XP service manual, they list 70 low's and 142.5 high's for both the 96XP and the 97 GSX.

I pulled the jets from the problematic GSX and found the following:

Mag side: 65 low and 142.5 high
PTO side: 65 low and 147.5 high (not a typo, 147.5)


My plan is to change the jets back to 70/142.5 and remove the accel pump and see if the condition improves.

Can anyone verify that my manual lists the correct jet sizes?

Can anyone verify what the jet sizes are for a 96 GSX (no accel pump)?

Thanks for the help!




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[purple_people_eater]

From 96 seadoo manual
CARBURETION GSX (5620) GTX (5640)
Carburetor Type Mikuni BN-40I-38 (diaphragm)
Quantity 2
Main jet 142.5
Pilot jet 70
Adjustment Low-speed screw 1 turn ± 1/4
High-speed screw 0
Idle speed (in water) 1500 RPM
Idle speed (out of water) 3000 RPM
Fuel Type Regular unleaded gasoline
Minimum octane no. 87
Fuel return line orifice MAG 0.8 mm (.031 in)
PTO 0.8 mm (.031 in)

1997

CARBURETION GSX (5624)
Carburetor Type Mikuni BN-40I-38 (diaphragm)
Quantity 2
Main jet 142.5
Pilot jet 70
Spring 80 g
Adjustment Low-speed screw 1 turn ± 1/4
High-speed screw 0
Idle speed (in water) 1500 RPM
Idle speed (out of water) 3000 RPM
Fuel Type Regular unleaded gasoline
Minimum octane no. 87
Fuel return line orifice MAG and PTO: 0.8 mm (.031 in)

 

[Krispy]

Thanks purple people eater!

So the same jetting with and without the accel. pump? Does that make sense to you?


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[Matt Braley]

Someone put 97XP carbs on your 97GSX.

 

[purple_people_eater]

yes, on the 787's the accelerator pump is used in the first part of the transition when the throttle is first applied. When the throttle rolls the cam, the squirt of fuel quickly provides the initial increase in engine rpm's which in turn provides the vacuum in the manifold to begin pulling fuel into the combustion chamber. after the carb transitions to the low speed circuit the the pumps job is done.

even if someone did put 97 xp carbs on there, the manual calls for the same jetting.

what could have happened is that a Previous owner or mechanic thought that because of the pump the low speed jet should be lower and replaced it.

 

[racerxxx]

If you truly want to make sure you would change the jets and leave the accel pump on. Test it to see if it's fixed, if not THEN remove the accel pump and test again. That way you can verify your results. I know, it's double work but it's the best way to cement your results.

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[Krispy]

If you truly want to make sure you would change the jets and leave the accel pump on. Test it to see if it's fixed, if not THEN remove the accel pump and test again. That way you can verify your results. I know, it's double work but it's the best way to cement your results.

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Yea, controlling one variable at a time. Makes sense.

Do you think it would do any harm to disconnect and plug the accel pump at the "T" where it splits into both carbs?

That way, if I determine I want the accel pump function I
can just unplug the pump output and reconnect the "T"

I guess what I am asking is , will it do damage to the accel pump to operate it against blocked lines?


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[purple_people_eater]

Yea, controlling one variable at a time. Makes sense.

Do you think it would do any harm to disconnect and plug the accel pump at the "T" where it splits into both carbs?

That way, if I determine I want the accel pump function I
can just unplug the pump output and reconnect the "T"

I guess what I am asking is , will it do damage to the accel pump to operate it against blocked lines?


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possibly. and they are really expensive to replace if it does harm it.

 

[Matt Braley]

I think if you jet the GSX like it's supposed to be then it will run perfect the first time if there are no other issues. If your gonna do it with the accel pump carbs then I would block off the failure prone accel pump and turn your low needles 1 1/4- 1 1/2 out. Those carb bodies have fewer holes in them for transitioning from low to high speed. Set your pop off to 30psi. Enjoy

 

[Krispy]

So the 97 GSX didn't have an accel pump? When did the accel pumps get added?

That would make sense as to why the jets weren't correct.

I think what I am going to try is dumping the accel pump fuel back into the return line by adding a small "T" to the return line, long enough to see how it runs.




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[Matt Braley]

The jets are not correct because they are for the XP. https://www.google.com/url?sa=t&rct...z4CICw&usg=AFQjCNFHYKmg4vnZNsNwUqpbhS_Ei_P4wQ

 

[Krispy]

The jets are not correct because they are for the XP. https://www.google.com/url?sa=t&rct...z4CICw&usg=AFQjCNFHYKmg4vnZNsNwUqpbhS_Ei_P4wQ

Good info Matt, Thank You!



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[Krispy]

I think if you jet the GSX like it's supposed to be then it will run perfect the first time if there are no other issues. If your gonna do it with the accel pump carbs then I would block off the failure prone accel pump and turn your low needles 1 1/4- 1 1/2 out. Those carb bodies have fewer holes in them for transitioning from low to high speed. Set your pop off to 30psi. Enjoy

Would you run XP or GSX jetting with the removed pump and low speed richened?


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