1990 Zephyr 550 California emissions style gas tank

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1990 Zephyr 550 California emissions style gas tank

Postby Old Kwack » 17 May 2020, 13:54

Hi, I purchased a replacement gas tank for my Zephyr 550 (thank you DaftRusty) that has the 2 extra vent fittings on the bottom for the California required emissions cannister and separator. Since my 1990 Zephyr is the 49 state version, how do I plug the extra vent fittings? Will a simple rubber plug suffice? Could I run a rubber hose from one to the other looping it around or do I need to run it to a PCV type one way valve? By plugging it am I affecting the pressure/venting in the tank? Sorry if this is a dumb question, but I'm not much of a mechanic. Thanks, -Dan
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Re: 1990 Zephyr 550 California emissions style gas tank

Postby DaftRusty » 24 May 2020, 22:08

I just now saw this......use quality rubber plugs exactly like the vacuum plugs on the carbs. Other types of plastic or rubber plugs will become brittle from exposure to the gasoline fumes.
As long as you reuse the locking gas cap from your other tank, it will have the pressure equalization ports (vent) built into it.
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Re: 1990 Zephyr 550 California emissions style gas tank

Postby Old Kwack » 25 May 2020, 02:43

Thanks again.
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Re: 1990 Zephyr 550 California emissions style gas tank

Postby Zaddict » 22 Nov 2020, 22:45

related question - looks like the left side vent on my CA 550 tank has hole in it somewhere inside the tank - fuel is spilling out the vent orifice. I thought having that vent open to atmosphere was important, but this thread leads me to believe I can just block it off.
Daftrussel - is the gas cap you're talking about stock, or did you get an aftermarket venting cap?
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Re: 1990 Zephyr 550 California emissions style gas tank

Postby Stereordinary » 23 Nov 2020, 01:21

Before I got my Zephyr 550, which is a California model that still has the extra emissions equipment installed, I had a Ninja 500 California model. On that one I was able to “delete” the extra equipment with a kit. All the information was available on the EX-500.com site, and I have heard that it’s the same basic process on any Kawasaki with the California equipment. Just look up “PAIR removal” for more info. Whenever I get around to removing it from mine, I’ll document and post it here.
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Re: 1990 Zephyr 550 California emissions style gas tank

Postby DaftRusty » 24 Nov 2020, 21:02

Zaddict wrote:related question - looks like the left side vent on my CA 550 tank has hole in it somewhere inside the tank - fuel is spilling out the vent orifice. I thought having that vent open to atmosphere was important, but this thread leads me to believe I can just block it off.
Daftrussel - is the gas cap you're talking about stock, or did you get an aftermarket venting cap?


This is a very difficult to explain without having great pictures of the Cali tank filler area (of which I have none) to explain which port is where and which one does what.
Sooo......If you remove the hinged gas cap and the decorative ring around the fuel cap you will see on a Cali tank two holes.
One hole is the drain that gets rid of fuel that might spill out from accidentally overflowing the fuel tank when filling it.
The other hole is the excess fuel vapor line that runs down the bottom of the tank and then goes to the fuel separator and charcoal canister.
The other 49 state fuel tanks DO NOT have the extra fuel vapor hole, just the overflow drain.
Of the two ports on the bottom of the left side of the tank (as when you are sitting on the bike) one port is the fore mentioned excess fuel vapor tube and the other is a tube that runs to the top of the INSIDE of tank and is open in order for excess raw fuel to return from the fuel separator.
It is entirely possible and common for both tubes to rot out and leak. But you will need to try blowing air trough the vent port in the filler neck and see if it is the one leaking. If it is, then just securely plug it up or preferably run some fuel line from the vent port to the fuel return port. As it will eventually start leaking as well, and this way it is a closed loop where no gas can ever leak out of the tank.
The locking gas cap is the same between the Cali model and the 49 state versions, the only difference is that the 49 state caps direct fumes directly to the atmosphere through a port in the bottom of the gas cap. On the Cali tanks, the gas cap vent port drains into the Cali specific vent tube and down to vapor separator/evap canister. So IF this is not the port that is not rusted through, don't plug that one up. IF it is the one that leaks fuel, you will need to saw off the little vent port on the gas cap, so the excess fuel vapors can escape into the atmosphere and not be directed down the (now plugged) evap tube. A issue I just thought about, is that if the the vapor tube is rusted and leaking, once the botoom port is plugged, it "may" also let excess fuel vapor escape out of the top side portion (under the fuel cap). Which also let the tank get rid of excess fuel vapor and pressure.
I hope some of this explanation makes some sense.
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