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Old 07-09-2012, 08:44 PM   #4423
nippybit's Avatar
Joined: May 2010
Location: Henderson, Nevada
Oddometer: 92
Gas Tank/Cap Venting

Originally Posted by snakepilot View Post
I have performed the above procedure, including installing a Renazco billet filler neck and an in-line one way valve to the scavenge fuel hose. My problem is that I am building pressure inside the tank (fuel vapors normal expansion).
I thought the one way valve would stop the denser fuel from escaping, while allowing some air to exit to accommodate fuel vapors and ,of course, allowing air to come in to fill tank as fuel is depleted. Do I need a different valve, or should I just vent the hose to atmosphere without any valve?

I would appreciate a comment from those that have performed this modification.



I have a full cannisterectomy on my 2010 R and I also have the Renazco filler neck and Acerbis cap. I am assuming here that you also have an Acerbis screw-on cap. If so the cap has a center vent recessed into it. I just use a no-slop short hose valve (about 2 1/2 inches high) which allows the tank to breathe but prevents excess fuel from escaping. The no slop valve just mounts vertically into the cap recess and onto the male vent. I have the factory vent hose, which is connected to nothing at either end, just tucked under the seat. No vacuum problems with my tank and I routinely fill it to its maximum capacity, i.e., 3.2 gallons.

Hope this helps.

P.S. No problems with gas tank venting in almost three years, with the bike left in the sun (in Southern Nevada summers), in the shade, etc. Got a good quality no-slop valve at Cycle Gear and it has never failed.
2010 KTM 690 R (sold 12/11/12)
Previous bikes (way too many to list here and what's the point)
Been riding mostly off-road since 1960--began at age 14.
Watch this space as I am about to say something really prophetic!

nippybit screwed with this post 07-09-2012 at 08:53 PM
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