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Tank vent line - question re 1-way in-line valve?


Gmc28
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Finally getting around to properly T-ing off my tank vent lines.  Trying to recall/work-out what the purpose is of the black plastic housing on the one vent line. Assume its a one-way valve, but can’t blow or suck on it, or so it seems, so before i go digging for what its really supposed to be thought I’d run it up the flag pole here…

cheers

 

128731A6-509E-49AE-BDDC-4DBBBB920BCE.jpeg

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It is there to save you from yourself. :whistle:

As in, you tip your V11 horizontal and this valve (supposedly) stops the fuel from exiting the tank vent.

Early reports of this valve becoming disoriented (out of plumb), creating a locked tank vent (aka: "Tank Suck"), led many to orient them into a convenient bin. :glare:

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Many thanks… makes good sense.  But am still wondering whether a guy should be able to either suck or blow through it, on the assumption that vapor or fuel would need to be able to move one way or the other for it to work.  But i suppose the orientation part of what you mentioned may explain that perfectly.…

The “tank suck” I’d initially think wouldn’t be an issue with my “married” vent lines, but I’d have to look closer at the plumbing to see if thats really true. 

I’ll probably pull it out and mess with it more to see if its actually working properly or not.  

Thanks again!

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One drains liquid from the top of the tank outside the fuel door (for fuel spills and rain water). The other lets air back in the tank after fuel is spent. I wouldn't connect them. In fact, European members have said their bikes came without any hoses at all. I have simply removed both vent lines and left the little fittings bare.

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12 minutes ago, Scud said:

One drains liquid from the top of the tank outside the fuel door (for fuel spills and rain water). The other lets air back in the tank after fuel is spent. I wouldn't connect them. In fact, European members have said their bikes came without any hoses at all. I have simply removed both vent lines and left the little fittings bare.

I wouldn't do that myself. If you have a fuel spillage when filling it'll dump fuel on a hot engine and the cap vents through the other port as well. It doesn't only vent air into the tank but also vapours out at a pre set pressure and keeps any vented fuel fumes which are more dangerous than the liquid fuel itself away from the hot area under the tank. Thats the funny sound you here sometimes after a ride and you park the bike. The tank venting pressure into those fittings and lines.

 

Ciao   

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Makes sense. Have you also heard that the European bikes came without any vent lines? In my experience, the ones that came on my bikes were loose and fell off anyway. 

But I think this is a better-safe-than-sorry thing. I think I might refit those lines - but clamp them to the vents and just run them so they will slip out easily with the tank.

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1 hour ago, Scud said:

Makes sense. Have you also heard that the European bikes came without any vent lines? In my experience, the ones that came on my bikes were loose and fell off anyway. 

But I think this is a better-safe-than-sorry thing. I think I might refit those lines - but clamp them to the vents and just run them so they will slip out easily with the tank.

No, I've never seen any bike like that. Ducatis are the same from the era and always had hoses. I run a plain hose from both connected with a Y piece up under the tank to the back of the sump in the traditional way but I have a joiner near the steering head so I can easily access it when the tank is installed. One of the benefits of having my front tank mount raised 40mm is there is not only more room under the tank but also more room between the tank and the wiring and fuel hose mess up near the steering head. The hoses on mine are also not negotiable as the nipples are now directly over my alternator regulator/rectifier. Fuel dropping directly on it in the event of any spillage or venting wouldn't be desirable.

Ciao  

DSC00921.JPG

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Raising the tank gave you a ton of room - you even moved the horns. Wow. I notice no hose between frame vent and airbox. Have you omitted that - or was that just mid-project?

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18 minutes ago, Scud said:

Raising the tank gave you a ton of room - you even moved the horns. Wow. I notice no hose between frame vent and airbox. Have you omitted that - or was that just mid-project?

No that was mid stage without the front mount finished. This is the final version.

 DSC00981.JPG

DSC01080.JPG

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On 2/27/2022 at 10:54 PM, Lucky Phil said:

No, I've never seen any bike like that. Ducatis are the same from the era and always had hoses. I run a plain hose from both connected with a Y piece up under the tank to the back of the sump in the traditional way but I have a joiner near the steering head so I can easily access it when the tank is installed. One of the benefits of having my front tank mount raised 40mm is there is not only more room under the tank but also more room between the tank and the wiring and fuel hose mess up near the steering head. The hoses on mine are also not negotiable as the nipples are now directly over my alternator regulator/rectifier. Fuel dropping directly on it in the event of any spillage or venting wouldn't be desirable.

Ciao  

DSC00921.JPG

So your 2 vent lines from the nipples are joined, and end routing “overboard” via the steering head area?  I’ve had mine joined near the nipples and then routed down the traditional way to the charcoal canister.  My intent on this go-around is to create a little union on right side where the joined/single line runs so i can simply disconnect it there and leave the nipple connections in place when i remove the tank. 

Is that a upgraded, niftier looking fuel filter there i see also?

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So, it’s fine to route the actual vent to the charcoal canister, but I would not want the cap/filler overflow routed there. The overflow should route any spill past the exhaust and away from the tire, I would think.

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5 hours ago, Gmc28 said:

So your 2 vent lines from the nipples are joined, and end routing “overboard” via the steering head area?  I’ve had mine joined near the nipples and then routed down the traditional way to the charcoal canister.  My intent on this go-around is to create a little union on right side where the joined/single line runs so i can simply disconnect it there and leave the nipple connections in place when i remove the tank. 

Is that a upgraded, niftier looking fuel filter there i see also?

I routed the joined lines forward so I had space for a connector that I could access before I removed the tank to make the process easy and simple. Mine both go overboard in the usual location as I couldn't devise a neat and unobtrusive way to locate the hose at the front of the crankcases below the steering head. I don't use a canister.

Yes that's an aftermarket fuel filter with a cleanable and replaceable filter to save space under the tank.

Ciao   

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