Gas Cap Compression with Altitude Change

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avejoe
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Gas Cap Compression with Altitude Change

Postby avejoe » Mon Dec 17, 2007 5:28 pm

When I head down from the hills my gas tank compresses and the gas cap cuts into the fender making it really difficult to remove. To address the issue I have to loosen the cap to allow air into the tank before I leave elevation. Is this a design defect or is it just my quad (07 KK)?

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Re: Gas Cap Compression with Altitude Change

Postby DAVE » Mon Dec 17, 2007 8:28 pm

avejoe wrote:When I head down from the hills my gas tank compresses and the gas cap cuts into the fender making it really difficult to remove. To address the issue I have to loosen the cap to allow air into the tank before I leave elevation. Is this a design defect or is it just my quad (07 KK)?

Thanks!
this is a new one for me.....most fuel tanks are vented, but with the new fuel injected quads I think the systems are a sealed loop. I have noticed that the yam 700 griz's gergle and burble. interesting. of course I am of no help to you :crybaby:
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Postby FishaHallic » Mon Dec 17, 2007 9:37 pm

I have not noticed that with mine but then again I have not rode it that much and the highest I had it was up near Verdi peak. Next time I ride I will check it out (HOPEFULLY THIS WEEKEND).

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Postby Ken » Tue Dec 18, 2007 4:35 am

My Polaris EFI has a breather hose. But I do notice it vents a LOT more gas than my carbed Quad.
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Postby Keith Strong » Tue Dec 18, 2007 5:56 am

Havent had that problem on mine at all????
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Postby NickD » Tue Dec 18, 2007 2:55 pm

Me neither... but then again I have never fueled up while on a ride. I fuel up at home and always make it back on the same tank. Next time we are riding at altitude, I will check out the filler cap to see what happens.
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avejoe
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Postby avejoe » Tue Dec 18, 2007 3:44 pm

The problem occurs when the tank is low when I leave altitude. There is more air in the tank to compress. Same thing when you use a water bottle in the mtns and by the time you get home it is scrutched up.

I will check my gas cap for any signs of a vent that may be plugged.

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Postby GrizzlyGuy » Tue Dec 18, 2007 6:11 pm

Your KQ should have a check valve somewhere in the fuel line. This is supposed to allow the tank to breath, while still minimizing the amount of fuel vapors that get released to the atmosphere (and prevent gas spillage if you roll over). Sounds like that is clogged or otherwise not functioning. My old Grizzly used the ole hole-in-cap technique, but the newer fuel injected quads have a check valve instead.
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avejoe
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Postby avejoe » Fri Jan 18, 2008 9:59 pm

There is a check valve above the gas tank and below the fender. I tried to remove it to clear it out and it appears I will have to remove the rear plastic to get at it.

That is more of a pain than making sure I burp the tank a few times on the way down the hill.

If there is any other way, I am all ears.
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Postby GrizzlyGuy » Sat Jan 19, 2008 1:31 pm

avejoe wrote:If there is any other way, I am all ears.
How about getting an older-style cap that has a hole/hose for venting, and put that on while transporting to/from the mountains? Then ride with your normal cap to keep from throwing off the EFI.

I don't know if KQ's use a cap the same size as Grizzly caps, but if they do, you could swing by a Yamaha dealer and buy a replacement cap for a 660 Grizzly. Those used the hole/hose design for venting.
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