GAS FILLER EXTENSION for CORBIN SEAT HOLE

Just picked up a '98 VMAX that had a Corbin seat on it. The po just left the seat loose to gas it up. Didn't like that so I saw where folks got a deck fill from a marine supply and 5" of filler hose to extend the filler neck. Thought it would be nice to keep the locking gas cap so I found a rusty gas tank on Ebay and sawed the neck off it to use (a little trickier than it sounds).
The only trouble is I discovered the tank vent also serves as an overflow when you fill the tank up to the top.

yeah...I just do what the PO did...done that for years and no issues with seat flying off or anything...

I am currently working to modify a custom Corbin seat. I hate taking off the seat every time I pump gas. It gets really annoying. So I'm looking to do this filler neck extension mod as well. I've done some forum searching and found some info on the mod but not a lot. I think I saw one post about the vent/ overflow but I can't remember what it was pointing out. As this pertains to my current mod, I would like to get more input on the matter.
The way I see it, there are a few solutions here:
One would be to leave it. This would cause gas leaking after fill up.
another would be to just block it off. This obviously would cause vent issues unless a cap with built in ventilation holes were used.
another solution would be to block off the old one and create a new one at the top of the added filler neck just before the cap with a hose leading down to where the old one ended. This I think would be the best solution.
This is all ignoring that irritating thing that happens to a lot of people on here when they fill up that if we wait a few seconds after topping off the gas level keeps going down.

I have planned on getting one of these:
http://www.amazon.com/Stant-41001-InStant-Fill-Gas/dp/B000RDDSN6

Which I think will vent easily enough but as far as there being an overflow what do you guys think?

I'd say the easiest solution is don't overfill the tank :ummm:

I like the extension and will be stealing this idea. I put a lot of miles on my bikes and will be adding an auxilliary tank to extend range which will solve the venting problem. However, when the aux tank isn't installed an in use, I will route the tank vent up next to the filler extension near the modified filler location before looping it back down via its normal route - fashioning a reversed drip loop. I just replaced Lola's fuel tank and this is a GREAT use for the old tanks filler neck.

I have planned on getting one of these:
http://www.amazon.com/Stant-41001-In.../dp/B000RDDSN6

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Maximus ... I would read the reviews on that Stant filler carefully. The cap looked like a good idea until I read the reviews. I would hate to soak the seat with fuel.

I'd say the easiest solution is don't overfill the tank

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Mike ... I wish I could resist the urge to get another tenth gallon into the lengthened filler neck. But, truth be told, I look at the extended capacity as a bonus from this fuel farkle.

Great input, 9.nub. hadn't thought of looping the vent hose up to filler extension then down. That would solve both the venting and the overflow.

As far a cap goes, I don't have a spare filler neck laying around and I had seen someone on here had used the stant instant fill. I liked the idea because it makes filling up that much less of a hassle. Just pull up, lift the corbin seat flap and gas it up. I am worried about the reviews but I figured if it works it'll be worth it. I also fiber glassed the tunnel of the corbin seat to add driver back support.

using the extra gas in the extension is irresistible. i hate waitin and watching the gas level go down at the pump. i'd rather just fill it all the way to the top and go and have it settle on the way.

I like the looped vent hose idea as well.
Just so you won't have to figure out the fill hose, I ordered 6" of stiff hose (sounds like the start of a joke:eusa_dance that was of 2" diameter. Cut mine to about 4 7/8". Wanted the hose to be square so I used a hack saw in a miter box. The heavier hose had metal wire in it, figured that out when the sparks started coming off my radial arm saw. Did not mod the neck on the existing tank at all, just slipped the hose on it and clamped it up.
It was also tough to get the cut off neck to go in the hose, rough edges wanted to hang up in the rubber. Spent some time and some pounding to get the thing in. In hindsight I would have pushed it through by starting the beveled side of the neck and push it to the other side using a dowel and a little 30w oil to lube up the hose.
Also if you cut the tank like I did you will have to grind off the flat part that is welded to the neck before you do your final cut. The factory neck is welded up with a piece of pipe stuck inside the neck at the weld where it goes in the tank

I got the old corbin been trying to figure out what to do extender, keep taking the seat off, or get a new seat.. I may keep it the way it is since the hole makes a great cup holder

Never took the seat off on mine , only on rare occasions, and I've got pretty big hands. I just kept the lock and spring latch well lubricated and then only had to turn the key and pull the cap off by the key. Then just put the cap back on in the correct position and give it a push. Once in a while it would go on cocked, then I pull the seat off. I had wing nut attachments I got at Home Depot epoxied on to the seat bolts. Just spin them off. Looked like this:

Itgoes said:

Never took the seat off on mine , only on rare occasions, and I've got pretty big hands. I just kept the lock and spring latch well lubricated and then only had to turn the key and pull the cap off by the key. Then just put the cap back on in the correct position and give it a push. Once in a while it would go on cocked, then I pull the seat off. I had wing nut attachments I got at Home Depot epoxied on to the seat bolts. Just spin them off. Looked like this:

View attachment 42169

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yep I did the same. Had bag of these at work and they seem to work just fine.
http://www.shear-loc.com/knobs.htm
these just press on to a socket head cap screw.
later, bill

Update: Did the loop in the overflow line so I could top it off.
Got 115 miles before the reserve switch had to be thrown on my mostly stock bike.
It takes quite a few top offs of the tank for the fuel to settle in.

I had my Corbin seat recovered a few years ago. The guy removed the flap and covered the access hole. I just lift off the seat to refuel. A bit of a hassle when the saddlebags are on, but the extra 30 seconds it takes are worth it to me, because simpler is always better in my opinion.. The seat never shifted or moved. If it did, I figure it would be because I crashed.. In that case I'd have other things to think about.

Hose is a cut off from older F-150 gas filler tube, extension is from a older import, don't know for sure what model, but old enough not to be the screw type cap. Cap is vmax, cut the metal tube so the cap is about one inch below the flap. Seat goes on and off perfectly.