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Discussion Starter #1 (Edited)
So last night, I was up riding on a really nasty, steep, and bumpy trail. I get to the top and notice there's splash marks in the dust on the back of the cvt cover. That's weird I thought because I didn't go through any water to splash up there. I get home and take the middle plastic off to see where and what is leaking. It was then I noticed a hairline crack in the frame right where the battery sits, and it's all wet. Turns out that the splashing was gasoline dripping from the crack! Why is there gas in my frame? Because Kawasaki runs the vent hose for the gas tank through the frame for some odd reason instead of just keeping it in a hose the entire length to the vent hose loom under the gauge pod!
Now, here's my theory why this happened. Three months ago, I was out in the middle of nowhere when all of a sudden, my Kawie wouldn't stay running on any slightest incline. Died like the carbs were flooded. I take the gas cap off and gas comes gushing out like a geyser. Yep, another *##^ing check valve had gone bad. This was like the 5th one! So I stick a $3 fuel filter I had kicking around in my glove box in there in lieu of a check valve. At that point, i was so sick of this bike burning through check valves that i didn't give a crap if i smelled gas vapors all day from the vent. I'd rather smell gas than have a fuel geyser and a stalled machine. But apparently, the way these Kawies are set up, it doesn't just let vapors out the vent.....it let's teaspoons of gas pass right through the frame!
So now I guess I'm stuck buying more damn check valves. The question is, why are they failing so often?? I ordered some generic aluminum body check valves off Amazon last time. Got a two-pack for $10 and put one on my machine, and one on my buddy's 650 Prairie. Both went bad in less than six months. I buy an OEM for $40 and it goes bad in less than six months. Wtf?
I see that Kawie has used different check valves for Prairies than for Brutes, and the older Brutes are different from newer Brutes. Does anyone know the difference? Should I try one for a 2020 Brute and see if it's any better?
 

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Never replaced the one on my '02 650 and I had that quad for almost 10 years. The one on my '06 Brute is still the original. Not sure why yours are failing at the rate they are. Are other guys having the same issue?
 

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Discussion Starter #3
Never replaced the one on my '02 650 and I had that quad for almost 10 years. The one on my '06 Brute is still the original. Not sure why yours are failing at the rate they are. Are other guys having the same issue?
I don't know. The one I put in my buddy's Prairie lasted as long as mine.
If I was using ethanol gas, I might understand it. But I've run less than 5 gallons of eth through it ever.
 

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I took the guts out of my check valve so it's no longer a check valve, 15 years ago. I've never had gas in the frame.
The vent should be at the very top of the tank, so very little gas should escape even if there's no check valve.
How do you even know that the valve is bypassing? How did gas escape when you took the gas cap off (if the quad was level at the time)? Did you remove the white spacer from the gas tank so you could fill it hard to the top?
 
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Discussion Starter #5
I took the guts out of my check valve so it's no longer a check valve, 15 years ago. I've never had gas in the frame.
The vent should be at the very top of the tank, so very little gas should escape even if there's no check valve.
How do you even know that the valve is bypassing? How did gas escape when you took the gas cap off (if the quad was level at the time)? Did you remove the white spacer from the gas tank so you could fill it hard to the top?
A gutless check valve would essentially be the same as the in-line filter I put in it. It should let the vapors come out and pass into the frame. You've never smelled vapors or had any gas come out? Maybe it has to do with big elevation changes then.

Each time a check valve failed, I could blow through both ends of it. A brand new one can only be blown through one end.
When they fail, it's like they plug up both ends and create a vacuum that boils the gas in the tank. Then when you take the cap off....gusher! I'm guessing that the vacuum overpowers the pump, and no gas is sent to the carbs because it just dies like it ran out of gas.

No, I have never touched the white spacer piece.
 

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Smelled vapors; rarely. Gas running out? Never.
 

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Discussion Starter #7
Smelled vapors; rarely. Gas running out? Never.
I recall one time down in Moab, it was 95 degrees and we were rock crawling with my Prairie and my uncle's Brute 750. After a couple hours, I could hear gurgling coming from the handlebars of the Brute. I looked under there and saw the steering stem was wet, and it smelled like gas really bad. Then a little while later, the Prairie started gurgling, but the stem was dry. After it cooled off, neither did it again the rest of the trip. Got home and pulled both check valves. His was shot. I could blow thru both ends with basically no restriction of air flow. Mine seemed partially shot. I could blow through both ends, but just barely on the one side.

You tear these little check valves apart and see there's just a little rubber nipple and valve in there. All plastic otherwise. Not made very well, yet the OEM ones cost almost $40. 😡
 

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My check valve in the Brute is stock, but I removed it from where it goes into the frame, put a hose on it and ran the other end along the frame beside the wiring harness to where all the vent hoses go. Never had an issue (touch wood). If I was having an issue as you describe, I'd remove the guts of the check valve, run a hose up to where all the vent hoses go, and put a small filter on there. That, or remove the check valve altogether, run a hose to where all the vent lines go and stick a filter on it. Done!
 
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Time to buy an injected BF. ;)

When I first bought mine I ran into a guy who owns an automotive shop in Monroe.
He told me that he had welded several BF frames but I don't remember him saying where they cracked.
I'd never heard that before.
 

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Discussion Starter #10
Time to buy an injected BF. ;)

When I first bought mine I ran into a guy who owns an automotive shop in Monroe.
He told me that he had welded several BF frames but I don't remember him saying where they cracked.
I'd never heard that before.
I've never heard of it before either. It cracked right around one of the factory welds. I guess 65 miles in the Uintas and 10 miles of Snake Creek was just a bit too much! I'm sure Hole In The Rock didn't help either!😆
 
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I would tend to think Murdock Basin would be a ball joint killer. :LOL:
 
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