Super Jet fouling plugs??

Waternut

Waternut

Customizing addict
Location
Macon, GA
Tried changing wires today for the heck of it, put in brand new plugs, and with careful throttle control, I was able to burn 2-3 gallons of gas. This was also coupled with turning the low speed screw down on the rear carb. Then I got careless and was paying attention to other things. I wasn't blipping the throttle constantly at that time and the rear plug fouled. Found out with some older plugs (which were good but used) that if I let the ski idle for 15-30 seconds, it'll foul the rear plug every time. I even tried turning the low speed screw from 1.5 turns out down to .5 turns out and it still fouled.

I didn't replace the needle and seat when I rebuilt the carbs but I did check the needle to see if it was worn and it looked new.
 
Waternut

Waternut

Customizing addict
Location
Macon, GA
I'm currently running 125 low jets. Guess I can try going down to 122.5 jets. Strange thing is, I was using those jets but it runs better with the larger jets...when it doesn't foul a plug. What's even more wierd is, I had to rejet after rebuilding this engine and changing from a stock intake manifold to an R&D manifold.
 
D-Roc

D-Roc

I forgot!
Location
Dirty River Rider
well the pilots and pop off over lap, i said to change the pilot because you didn't mention any bad hesitations or the throttle responce. the change of intakes may have been better off with just the pop off change but its not my ski and i haven't rode it to see what it is doing. increasing your pop off will delay when the main jets kick in and will be like "leaning out the pilots" kinda. maybe try the 122.5 pilots and then if that doesn't make it run as good but not foul plugs, lower your pop off a bit.
 
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D-Roc

D-Roc

I forgot!
Location
Dirty River Rider
the needle seats may be the problem on the rear carb too. if it is leaking fuel, the pilot/lower throttle position circuits will be getting the added fuel and fouling up your plug. this could explain why one rear carb/cylinder is doing it and not the front with the same jetting. also, do you have a pop off gauge? you cannot tell a damn thing about your pop off between the two carbs with out one of these tuning tools.
 
Freerider77

Freerider77

Location
Port Angeles
My new superjet (97) hasn’t run right since I bought it in July. It used to run fine on the first start then bogged out on second startup. Now it drops a cylinder right outta the gates. I began troubleshooting with the help of many surf buddies. Wiring was questionable at best, so started there, along with cleaning all battery connections (outside the ebox). Now fires up like a bat outta hell but still drops a cylinder first start, almost wants to fire correctly at times, putting out almost full power. However, second start it doesn’t come out of it and stays on one cylinder until I fall over.

Proper Ground wire
Proper electrical wiring for the bilge pump
Rebuilt the carb
Fixed the leaky exhaust that was choking the engine of oxygen.
Result: Runs much better. I can tell the big difference these fixes made. However, still drops to one cylinder as soon as I put in the water, mount and take off. Add 270 lbs (me ) and it taps out. Any thoughts? I will check those plug cables for corrosion under the caps. If this fails to be my elusive culprit here, I will take to my local guy for compression check.
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Freerider77

Freerider77

Location
Port Angeles
I have not tried that, nor can I even tell which cylinder is misfiring. But i see what you‘re getting at, if a different cylinder dropped after switching plug wires, the problem would most definitely be a bad plug wire, badly corroded/oxidized perhaps.


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