97 GSX bog from idle. Pop-off too low?

[Krispy]

So I have a stock 97 GSX (Accelerator Pump, Dual Carb, Factory Airbox). I have noticed a rich bog immediately upon acceleration.

Carbs rebuilt, fuel lines and selector replaced.

When I rebuilt my carbs I think I may have set my pop-off a little low (the springs in the carbs had the pop-off set so high I couldn't get a reliable pop-off test 40 PSI+) So I installed some springs I had on hand that resulted in a 15 PSI pop-off.

I have a feeling that the low pop-off coupled with the factory accelerator pump is causing an overly rich condition, when I apply choke during the bog things get worse.

Suggestions on fixing the problem? Raise pop-off pressure? Lean out the low speed jets? Remove accelerator pump?

 

[racerxxx]

The way I look at is, if the old springs were original, re-use them. Have you swapped back and tried it?

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[Mekanix]

That thing the year before without the accelerator pumps has a pop off of 38 so going down to 15 is insanely rich I would think! I wouldn't even go that low in my non accell carbs.

 

[Krispy]

Ok, since starting the thread I tore into the carbs again.

I had one set at 25 and the other at 27. I mistakenly thought they were at 15.

I put back the springs that were in the carb when I tore it down (super bright silver) and my pop off tester hose wouldn't stay on the fuel inlet. Pop off was pegging my gauge at 50 psi. (EDIT) 1.5 n/s

I have trimmed 2.5 coils off and stretched those springs, now I am popping off around 37.

I will see how it works out if I can finish assembling and make it to the lake.

37 seems really high to me...



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[Mekanix]

I could believe that or higher. Depends on what is in there for pilot jets.

 

[Krispy]

Well, just got back from the lake.

The GSX is running better than before. Still a bit of hesitation until up on plane, but much better than before. The RAVES seem to open later in the GSX than my XP. Did 54 on the GPS.

The GSX may be operating just as it should. I am just trying to compare it to my XP, and it literally jumps out of the hole.

 

[Mekanix]

The gsx does just jump right out of the hole though. At least with mine I can give it anything and it will just pickup without hesitation. I mean 0 to ''on the raves'' (5500) instantly.

 

[racerxxx]

Not to sound like an a hole, but you just f'd up. You never cut or stretch a spring. Regardless of what your pop off was you should have water tested it first, or at least I would have. You have to establish a base line before you start changing stuff.

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[Krispy]

Not to sound like an a hole, but you just f'd up. You never cut or stretch a spring. Regardless of what your pop off was you should have water tested it first, or at least I would have. You have to establish a base line before you start changing stuff.

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Why is removing some free length from the spring a bad idea? Pop-off was out of spec and now it is back in spec. It isn't an a-hole move to tell me what was done was wrong, but it isn't constructive unless you explain why.

I purchased this ski non running from a guy who left intake grate bolts off and fashioned vts linkage from all-thread. The ski needed the carbs cleaned and fuel lines changed. O

Before taking it to the lake I pulled the carbs to change the fuel lines and verify carb settings, I found a leaky needle and seat, and low speed adjusters out of spec, along with an excessive pop off pressure. On the plus side all the components inside the carbs were in good shape, recently replaced.

My baseline is the factory settings on a stock boat, not what some shade tree mechanic (other than myself) has done.

Edit: After reviewing my machine design book, I realize that removing coils actually increases the spring rate. I think I took length out of the spring and reduced the preload on the arm/needle seat.

I could see how this could cause issues dynamically if the function of the n/s isn't binary but requires flow metering that isn't on or off.



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[AdamXP800]

Let me see if I can find [MENTION=16022]Dr Honda[/MENTION] quote on this. It is a very very bad idea to cut the spring

 

[AdamXP800]

http://www.seadooforum.com/showthread.php?36634-Carburetor-pop-off-pressure

 

[Krispy]

Let me see if I can find [MENTION=16022]Dr Honda[/MENTION] quote on this. It is a very very bad idea to cut the spring

If you can find it let me know. I am interested.

Read my edit above, I have a theory as to why this is.


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[AdamXP800]

Link posted above

 

[Krispy]

http://www.seadooforum.com/showthread.php?36634-Carburetor-pop-off-pressure

Awesome find, thanks! confirms what I figured and mentioned in my edit.

And the carbs come back off!

Who wants to trade beer for the proper springs?





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[AdamXP800]

Which ones do you need? I have a ton of them

 

[AdamXP800]

I believe I have several of each gram spring

 

[racerxxx]

You don't cut the springs, that's why there are several different colors, and reverse wound springs. You adjust the pop of by changing those. You'll never be 100% correct on cut or stretch. I totally get the spec on pop off, but I would have first tried they original springs.

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[Krispy]

Which ones do you need? I have a ton of them

I need 2 80 gram springs. I believe they should be black.

 

[racerxxx]

Looks like you've got the data, slow at typing on the ole phone tonight.

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[Mekanix]

What needle and seat do you have in there?

If its the stock 1.5 that means you need the black spring for non-accell pumps but that maxes out at 48 psi but normal is around 36-40 just the way it is when you install it with new parts.

I'm guessing that it had the 115 g spring in there if you can't get it to pop after 50 psi !

The manual on page 137 I think show's the chart of spring's vs seat size and pop off pressure.

1.5 NS with 80 g spring gives you 33 psi +- 10psi.
1.5 NS with 115g spring gives you 76+- 15psi. I think you had these to start off with.

 

[Krispy]

What needle and seat do you have in there?

If its the stock 1.5 that means you need the black spring for non-accell pumps but that maxes out at 48 psi but normal is around 36-40 just the way it is when you install it with new parts.

I'm guessing that it had the 115 g spring in there if you can't get it to pop after 50 psi !

The manual on page 137 I think show's the chart of spring's vs seat size and pop off pressure.

1.5 NS with 80 g spring gives you 33 psi +- 10psi.
1.5 NS with 115g spring gives you 76+- 15psi. I think you had these to start off with.

Thanks to all who helped.

I have 1.5 n/s in there now just checked my spare.

I have a bunch of jets and a handful of springs, but none gave me what I was looking for.

I need to locate 2 80gram black springs.


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[AdamXP800]

I just put the black ones in my xp. I might have a few more, if not I can get them from a local guy 2 doors down and ship them Monday to you. He never charges me for the springs

 

[Krispy]

I just put the black ones in my xp. I might have a few more, if not I can get them from a local guy 2 doors down and ship them Monday to you. He never charges me for the springs

Thanks, if you come up with something let me know. I'll owe ya one after the group ride we are supposed to be doing lol!


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[Strizzo]

With your pop off setting, you have two ways of adjusting the pop off. You can change the spring, and you can bend the arm. With your lighter spring you can probably get pop off up to 25 psi or so by adjusting the arm, and you don't have to worry about the arm being too high. With the lower pop off you should be able to get it working right by running the LS needle an 1/8-1/4 turn further in. Also make sure your accel pump still has the restrictor in it otherwise you'll be blasting the full shot every time the throttle opens.

Eta: you should be running a 1.5 needle and seat, you said 2.0 earlier.

 

[Krispy]

With your pop off setting, you have two ways of adjusting the pop off. You can change the spring, and you can bend the arm. With your lighter spring you can probably get pop off up to 25 psi or so by adjusting the arm, and you don't have to worry about the arm being too high. With the lower pop off you should be able to get it working right by running the LS needle an 1/8-1/4 turn further in. Also make sure your accel pump still has the restrictor in it otherwise you'll be blasting the full shot every time the throttle opens.

Eta: you should be running a 1.5 needle and seat, you said 2.0 earlier.

I went back and edited, I am indeed running a 1.5 n/s and my first apron gave me 25-27 psi.

What restrictor are you referring to? I replaced the fuel line with tygon but kept all the stuff in line, is it the little green valve?


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