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Discussion Starter · #1 ·
07 ninja 650r

about a month ago I tore the bike down to just frame and left the engine in. Kind of a pre summer inspection... ok maybe a little more then an "inspection" lol

Replaced quite a few little parts (bolts, nuts, springs etc) and I did have to replace throttle body with used one from ebay. I stripped my buttery valves on the old one.

I completed the rebuild just a little bit ago. I let the fuel pump prime about 4 times before starting. Fired right up for a second, fired it again and she sang beautifully. I only let it run for a min because I was trying to let new fluids cycle and top them off and 3 weeks worth of PB blaster was burning off the exhaust header.

After shutting it off and fuel cap closed, massive amount of air came gushing past the cap seal. I opened it up real quick to help it exhaust out (it was alot). I let the tank breath for a min, it has been sitting in the corner of my hot garage for a couple weeks so I figured vapors finally found a way out.

Came back a few mins later and closed the cap, raised bike off kickstand to push into garage and instantly started gushing again.

Would I be correct in assuming it's just trapped vapor build up? Or maybe something to do with the used throttle body I should look at?

I'm 99% sure all electrical and vacuum lines are hooked up correctly because I labeled every single line with blue tape and only removed the tape after they were plugged in.

****
NON Cali model
Aftermarket exhaust
Snorkel delete
PAIR valve bypass
 

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Was the tank full, 1/2, 1/4? Gasoline contains many things, including volatile fluids, like butane and propane. This will come out of it when the tank is shaken or warmed. Your tank has a vent to release any pressure, and to allow air in when you use the fuel.

Try a search for "07 ninja 650r fuel tank pressure" and you will find many discussions of this.
 

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Discussion Starter · #3 ·
Was the tank full, 1/2, 1/4? Gasoline contains many things, including volatile fluids, like butane and propane. This will come out of it when the tank is shaken or warmed. Your tank has a vent to release any pressure, and to allow air in when you use the fuel.

Try a search for "07 ninja 650r fuel tank pressure" and you will find many discussions of this.

Over 3/4 full. Have the service manual open to double check connections and everything is correct. Nothing is kinked. Maybe I got some varnish buildup in the vent of the cap. Tank was sitting nose down on the floor the whole time, maybe fuel soaked into cap.

I'll check it out
 

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If your cap is anything like the ones Suzuki uses, it has a small check ball, to prevent fuel leaking if the bike is on its side. Watch for it to fall out when you open the cap.
If that ball is stuck, pressure will build in the tank.
 

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Discussion Starter · #5 · (Edited)
If your cap is anything like the ones Suzuki uses, it has a small check ball, to prevent fuel leaking if the bike is on its side. Watch for it to fall out when you open the cap.
If that ball is stuck, pressure will build in the tank.
No check ball, but a series of needle size path ways molded into a rubber gasket. I disassembled the cap about a year ago because the lock was binding up and thought it was interesting

EDIT: took some pics.
 

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07 ninja 650r

After shutting it off and fuel cap closed, massive amount of air came gushing past the cap seal. I opened it up real quick to help it exhaust out (it was alot). I let the tank breath for a min, it has been sitting in the corner of my hot garage for a couple weeks so I figured vapors finally found a way out.

Came back a few mins later and closed the cap, raised bike off kickstand to push into garage and instantly started gushing again.

Would I be correct in assuming it's just trapped vapor build up?
Yes, you would be correct! My first bike was a Ninja 300 and it did that exact same thing anytime the weather was warm. When I inquired, the veteran riders said that it is common to Kawasaki bikes (at least their sport bikes) and nothing to worry about...
 

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Discussion Starter · #7 ·
[SOLVED]Air gushing from tank cap

It was the cap. Turns out there's TWO check valves. One for positive and one for negative pressure.

Cleaned them both and good to go.

I originally thought this was about to be some huge ordeal because of the used and untested throttle body sending the fuel pump into a frenzy.
 

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Glad you found the answer and it was a simple solution.
 

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Discussion Starter · #9 ·
Now I just have to figure out why the flux capacitor isn't holding. It keeps dumping its charge to ground. I can't hit highway speeds unless it can hold no less then 1.21 gigwatts otherwise I'm stuck in the slow lane. How do I go about diagnosing this?
 

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Now I just have to figure out why the flux capacitor isn't holding. It keeps dumping its charge to ground. I can't hit highway speeds unless it can hold no less then 1.21 gigwatts otherwise I'm stuck in the slow lane. How do I go about diagnosing this?
Your Mr. Fusion is malfunctioning. Probably a tough bit of banana or orange peel got wedged under the cap.
 

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Now I just have to figure out why the flux capacitor isn't holding. It keeps dumping its charge to ground. I can't hit highway speeds unless it can hold no less then 1.21 gigwatts otherwise I'm stuck in the slow lane. How do I go about diagnosing this?
I have a Delorean. Are you still using the Lucas harness or did you upgrade to Bosch?
 
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