Super Jet Stock 2008 701 bogging down

S

shot26

Location
Forest Lake, MN
My recently acquired ski has not run well since I got it. Boggs down with intermittent spells of power. Runs well for a couple seconds after pumping the primer. Seems like it's not getting enough gas when throttling. Idles perfectly.

I've rebuilt both carbs and replaces fuel filter without any improvement. Given that it runs well when pumping the primer it sure seems fuel related to me.

Any ideas?




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mike b

mike b

Michael "Mayhem" Bevacqua aka MikeyChan
Location
California
check that the filter in the carb is clean, both jets are clean, and that the needle and seat is moving freely is my guess to start. Check for good flow in the fuel lines. Also one way check valve in the tank. Just somewhere to start that is all fairly easy and free.
 
S

shot26

Location
Forest Lake, MN
mike b said:
check that the filter in the carb is clean, both jets are clean, and that the needle and seat is moving freely is my guess to start. Check for good flow in the fuel lines. Also one way check valve in the tank. Just somewhere to start that is all fairly easy and free.
Click to expand...
Thanks Mike. I'll take another look tomorrow.


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All stock 701

All stock 701

Location
Pasadena, MD
What parts did you replace while rebuilding carbs? Not questioning your intelligence just trying to give a few ideas that may help.
Did you replace the fuel pump diaphragms inside the carbs? They may be weakened and in need of replacement. Ethanol ruins all the rubber parts inside of carburetors and they need to be replaced.
 
S

shot26

Location
Forest Lake, MN
All stock 701 said:
What parts did you replace while rebuilding carbs? Not questioning your intelligence just trying to give a few ideas that may help.
Did you replace the fuel pump diaphragms inside the carbs? They may be weakened and in need of replacement. Ethanol ruins all the rubber parts inside of carburetors and they need to be replaced.
Click to expand...

It is my first carb rebuild so feel free to question anything I am doing / or did.

I did take everything apart and cleaned. Blew out all the chambers with an air hose an replaced all the seals, gaskets, o-rings and filter.

The only things I didn't replace were the needles, seats and springs. (I didn't have a pop off gauge so I figured I'd skip for now.

Here is a video of what it does when throttled.



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Graham Buchan

Graham Buchan

Location
Cold Lake, AB
What about reeds? I have this problem and it turned out to be my reeds
14edaa2a52a6b8f44547757ef7db7179.jpg



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S

shot26

Location
Forest Lake, MN
Graham Buchan said:
What about reeds? I have this problem and it turned out to be my reeds
14edaa2a52a6b8f44547757ef7db7179.jpg



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Click to expand...
I checked my reeds. They are perfect.

I have come to the conclusion that the tamper proof adjustment screws on the carbs need to be removed and cleaned. I drilled out the plugs and pulled the screws out. The low jet and adjustment appears to be clogged. I'll update you when the new T screws arrive and are installed.


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T

thomps33

I wouldn't rebuild carbs without a pop-off gauge. You are blindly throwing darts at a board trying to hit the bullseye. You have no idea what the pop off is set at or if the carbs are sealed without one.

Given that it idles fines, but is starving for fuel when you give it gas means the hs jet might be plugged, the needle and seat might be leaking or the pop off pressure is wrong. You need the pop-off gauge to diagnose that (besides the hs jet. )
 
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S

shot26

Location
Forest Lake, MN
thomps33 said:
I wouldn't rebuild carbs without a pop-off gauge. You are blindly throwing darts at a board trying to hit the bullseye. You have no idea what the pop off is set at or if the carbs are sealed without one.

Given that it idles fines, but is starving for fuel when you give it gas means the hs jet might be plugged, the needle and seat might be leaking or the pop off pressure is wrong. You need the pop-off gauge to diagnose that (besides the hs jet. )
Click to expand...

I picked up a pop off gauge last week. Both carbs were adjusted to 28lb pop off.

I was able to adjust the screws this weekend and clearly that was the problem. It's still not right but I'm on to it.

Now I need to figure out correct screw settings and jets to make it run correctly.

I am reevaluating the jets and screw settings now.


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T

thomps33

I think stock is around 55 psi... it uses the 115 gram spring. If you were using an aftermarket intake you could go down to 95 gram springs to lower the pop off.
 
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