[greg328]

Hi everybody,
Did a search on this topic but found limited info. Parts tables are inconclusive as well. Here's my issue:

After a ride on my 2007 1098, I'll park it in the garage, and then it fills the space with serious gas fumes. Not good.

I'm the second owner, first owner did the charcoal canister delete. A few years ago when I acquired the bike I removed the tank to coat the inside with Caswell Coating (working great by the way, no tank expansion in several years!)
At that time I noticed that both lower tank vent nipples had no hoses attached to them.

I'd like some clarity on those two nipples' function. Do they vent from the gas cap? One from the gas cap area, and maybe one from the tank itself? A while ago, after a complete fill-up I put the bike on its side stand and a bit of fuel leaked from the vent nipple area. I suspect the gas cap vent filled with fuel at the angle and bled down to the vent. This sound about right?

Today I removed my tank again to inspect everything, with about 1/2 gallon of gas still in it. I have the Motowheels quick-release fuel line couplers so super easy to do! I angled the tank rearward and observed the two nipples, and indeed they did leak a drop or two of fuel. So they are clearly venting directly to the atmosphere. Not sure why the PO left these vent nipples unattached, but now I'm fairly certain this is the source of my fuel odor.

So, my question is: what do I do with these open vent nipples? I obviously can't just attach a drain hose to aim downward, I'l still have fumes venting to the atmosphere.
And I can't just cap them off, right? The tank has to breathe to prevent vapor lock, yes?

I thought I saw mention somewhere of running these 2 hoses to a -T- and then sending that single hose back into the throttle body. Is this a solution? If so, where does that attachment occur?

Any advice will be most appreciated.

Best,
Greg
Houston TX

 

[erick1670]

Both go to the bottom..... I just did the Caswell in my tank for my rebuild.
One hose is for the overflow and the other to vent the fumes from the gas.

 

[greg328]

I appreciate the response. Are you saying to just attach hoses to both and route them to the bottom of the bike? This will still emit fumes to the atmosphere. I'm trying to avoid this, because of the immense fuel odor.

Has anybody directed them back into the throttle body? On mine, the main fuel line feed has a -T- into the top of the throttle body/airbox (large black box under the tank) as the line runs down towards the front (I assume to the fuel injectors?)

Greg

 

[erick1670]

Yep... just attach hoses to them. That's how they come from factory, my Aprilia also has them.

 

[greg328]

Did 1098s from the factory originally run these vent lines into the charcoal canister? I find it hard to believe that the factory would vent the tank directly to the atmosphere. I'll consult my parts tables again. I do not want to just move the fuel vapor lower to the ground, this does not solve my issue.

What are people doing with these tank vents? Surely most of you have removed the charcoal canister.

Thanks,
Greg

 

[greg328]

Ok I've found the charcoal canister remove how-to thread, should provide some answers.
Greg

 

[rubbish]

Originally one of them went into the charcoal canister, and another one from the charcoal canister down to the belly pan (through it actually) along with the other hose from the tank. It has to vent somewhere, but I've never smelled any gas, so if you're smelling a strong gas odor, it might be something else. I also removed my charcoal canister and noticed no difference at all. And that was even in a single-stall garage with no windows or any ventilation, aside from the crack under the door.

 

[rubbish]

You should definitely attach the hoses though, just to avoid fuel drops leaking on your engine cases, clutch, and other parts in that area.

 

[greg328]

Thanks rubbish

 

[greg328]

OK, I ran hoses off both tank nipples to the bottom of the bike, but I'm still getting serious gas fumes in the garage. I now suspect the gas cap seal. It's close to 9 years old now, so maybe it needs replacement. The rubber seal is a little bit stiff at this point.

Question: Can that rubber gas cap seal be replaced by itself? Or does the entire gas cap need to be replaced?

Thanks,
Greg G