Super Jet Holy crap backfire??

Byeai

"Cheetos-Man"
Location
Melbourne FL
Make sure you cable is coming back and not sticking and retighten the manifold bolts and carb base bolts

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JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
Make sure you cable is coming back and not sticking and retighten the manifold bolts and carb base bolts

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I pulled the carbs made sure they were in sync, made sure manifold was tight, throttle doesn't stick and returns to idle just fine, turned both high and low speed adjusters half a turn, and put a brand new base gasket on the carbs. And guess what it still runs away, this problem also is happening with Dirtyaces ski we have the exact same problem. there are no air leaks at all. now if anyone knows what jets, springs, screw adjustments, and needle valves are needed for this setup please let me know because every one says something different?
 

tightithrash

Zack Bright. I Thrash.
Site Supporter
Location
Oceanside, CA
are your fuel lines stock of aftermarket? if they are old you could be leaking air into the lines where it plugs into the carbs or on the tank side. or possibly a cracked line. if there aftermarket and colored clear, look for air bubbles in the lines. make sure all the fuel lines are ziptied.

maybe your crankseals are toast and leaking air.
 

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
are your fuel lines stock of aftermarket? if they are old you could be leaking air into the lines where it plugs into the carbs or on the tank side. or possibly a cracked line. if there aftermarket and colored clear, look for air bubbles in the lines. make sure all the fuel lines are ziptied.

maybe your crankseals are toast and leaking air.

I honestly haven't checked the lines they are oem and 15 years old. Motor ran great 3 months ago but I will do a pressure test to make sure all is with in spec. I'm seriously debating just taking the ski out and if it blows it blows.

Monday I will put 2.0 n/s and 95 gram springs. If its not the fuel line.
 

Proformance1

Liquid Insanity
Location
New York Crew
Describe exactly what you changed, fixed or repaired to the crew here. If you rebuilt carbs, did u use OEM or mikuni only parts or aftermarket? Think and describe all that you did, and also if it was fine before.
 

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
Ok let me start off with the last time i took it out. It was 12/26/12 and the ski ran fine but i when i went to flush the ski out it kinda hung the rpm a little but at the same time the carbs were not synced up and i turned the fuel selector off..

The ski has been stock since i bought it last year only thing engine wise was Pro-K FAs

During the winter i replaced all gaskets because i wanted to paint some pieces. i also reassembled most gaskets with Yamabond 4 as per some members on here i figured it couldnt hurt. carbs were rebuilt with wsm gaskets but i only replaced 2 of them cause when i was cleaning them out i ripped one and replaced both diaphragms.

On to mods

The only mods i did were ADA head 35cc domes and a riva red pipe.

Carbs are oem 38s with 135 main 70 pilot 115g springs and 1.5 N/S as per jet maniac and many others. screws are set to 2 high and 2 low because i was trying to fix the run away.
 
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tightithrash

Zack Bright. I Thrash.
Site Supporter
Location
Oceanside, CA
Ok let me start off with the last time i took it out. It was 12/26/12 and the ski ran fine but i when i went to flush the ski out it kinda hung the rpm a little but at the same time the carbs were not synced up and i turned the fuel selector off..

The ski has been stock since i bought it last year only thing engine wise was Pro-K FAs

During the winter i replaced all gaskets because i wanted to paint some pieces. i also reassembled most gaskets with Yamabond 4 as per some members on here i figured it couldnt hurt. carbs were rebuilt with wsm gaskets but i only replaced 2 of them cause when i was cleaning them out i ripped one and replaced both diaphragms.

On to mods

The only mods i did were ADA head 35cc domes and a riva red pipe.

Carbs are oem 38s with 135 main 70 pilot 115g springs and 1.5 N/S as per jet maniac and many others. screws are set to 2 high and 2 low because i was trying to fix the run away.

my-eh-face--large-msg-1132935610-2.jpg


i personally wouldnt use wsm on anything.
 

JT_Freeride

John Tetenes @Jtetenes
Location
Long Island
Update: I put 2.0 N/S in with the 95g springs and the runaway went away, so i took the ski out in some seriously choppy water and when i first went out the ski was amazing low end was good and mid was amazing, but after about 5 mins i couldnt get the ski to go past idle it would sound like its hitting a rev limter so i stopped pulled the hood to make sure i didnt have a exhaust leak and there was none so i tried again and exact same thing sounds like it hitting a rev limiter. To describe the sound it kinda sound like a car with 2-step. what could this be its intermittent. thanks all help is appreciated.
 
i know it sounds dumb, make sure your pulse line and fuel line arent backwards, i crossed mine once in a rush re-jet and wow what a head scratcher, had similar issues as you, it would run normal for a bit, then at half throttle or so it would bog down like heat senser or rev limiter was engaging, usually followed by a bang, and if you are using a heat senser it may have gone bad
 
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Location
Kiowa, KS
are you sure that the cut wires aren't getting bridged with water causing the ebox to think the motor is overheated? I disconnected my heat sensor inside the ebox
 
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