Faux Tank to aux tank mod

[davesax36]

So I think I might try this as an option. I believe it's an FZ1 tank that's been cut up more than a little bit. I have a spare faux tank cover, and I'm thinking that I might have a local shop cut the bottom out of an FZ1 tank (which they have) and welding it to my extra faux tank. This would eliminate problems with mounting. I'd have a 5/16" main feed hose cut off one of my extra tanks, seal up the current filler neck and vent line, and use the FZ1 filler cap location to fill the whole tank. I guess I could try to use an even bigger connecting line to plumb to the stock tank, but I think with proper venting, it would fill at a reasonable rate. This would give me a greatly increased fuel capacity and a pretty angry look. What fabrication issues am I forgetting, other than the possibility of the faux tank being really thin and a massive pain to weld?

 

[Shorty]

It might be an idea to, instead of blanking off your original tank vent, to plumb it back up to the FZ1 tank to avoid ending up with a massive air pocket at the top of the original tank. Regarding the welding: having done a few cut'n'shuts on Harley tanks before I've found that it's best to use a TIG welder as opposed to a mig because it causes less heat. Less heat = less distortion in the tank. Be sure to have both weld surfaces absolutely spotless. The slightest bit of crap on there and you could end up with a pinhole in the weld and therefore a fuel leak. When I have welded tanks before, even though I'm happy with my weld job, I always use a good epoxy tank liner after washing the tank out with a mild acid just as insurance. The last thing you want is a nasty fuel bubble under your beautiful new paint job.

 

[davesax36]

It might be an idea to, instead of blanking off your original tank vent, to plumb it back up to the FZ1 tank to avoid ending up with a massive air pocket at the top of the original tank. Regarding the welding: having done a few cut'n'shuts on Harley tanks before I've found that it's best to use a TIG welder as opposed to a mig because it causes less heat. Less heat = less distortion in the tank. Be sure to have both weld surfaces absolutely spotless. The slightest bit of crap on there and you could end up with a pinhole in the weld and therefore a fuel leak. When I have welded tanks before, even though I'm happy with my weld job, I always use a good epoxy tank liner after washing the tank out with a mild acid just as insurance. The last thing you want is a nasty fuel bubble under your beautiful new paint job.

That's what I was looking for. If I plumb the vent line up to the other tank, does that mean it's just all full of fuel or do the two air passages have to connect? I have a guy that will definitely TIG it up for me. I gotta see how much of the tank I'll have to cut off to match it to the original cover. I think this is gonna be my best solution.

The guy whose bike this is said it's a "tankatrappe label self's building" ... Pretty sure that translates to custom fake tank...

 

[Shorty]

That's what I was looking for. If I plumb the vent line up to the other tank, does that mean it's just all full of fuel or do the two air passages have to connect? I have a guy that will definitely TIG it up for me. I gotta see how much of the tank I'll have to cut off to match it to the original cover. I think this is gonna be my best solution.

The guy whose bike this is said it's a "tankatrappe label self's building" ... Pretty sure that translates to custom fake tank...

Ideally you'd want the vent line to go at least "near" to the top of your new tank. This is achievable by having your mate TIG a tube to the inside of your new tank before the base is installed. Note: it only needs to be tack welded to hold it in place. Remember the more heat you put into this thing the more it WILL distort and the more panel work will be required when it comes to paint prep time. Make sure you have enough length of tube hanging out the bottom to make installation easier. 3 or 4" is good as you can cut it off later. You could just put your original tank breather into your new tank setup at the bottom of your new tank only but that would mean that the air that's attempting to escape from your original tank would be fighting the fuel coming in. This would mean that you'd need to spend half your ride time at the gas pump waiting for the air to get out. Not a fun day...haha

Custom "fake" tank? Yuck! The guy who I bought my bike from "LOOSELY" screwed on a heap of fake parts and his own version of custom parts including a homemade rear light/plate bracket which he fixed to the rear guard (fender) with body filler.?.? This fell off on my first ride home:bang head: so the first thing I had to do after arriving home was repair his "CUSTOM" work and replace three feet of burnt out wiring. Not an experience that I was anticipating.....

 

[davesax36]

I don't know how fake it is. I'm not sure if it feeds the stocker or not. I'm gonna go talk to this shop when I get home. If I can get it done for a reasonable price, I'm going for it.

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[Shorty]

Sweet. Well I hope I've helped a bit and I hope it all works out for you..

 

[johnblaid]

i'm actually considering having two stainless steel 3 gallon gas cans styled like side bags made for mine. that would give me 9 gallons and a really spectacular fire in a crash. The bike is light enough for me to handle the extra weight. And If they look really nice and I paint them to match the bike, maybe no cops will notice.

 

[davesax36]

Why would cops care? They make side cases for the big BMW bikes that have fuel tanks in them.

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[srk468]

Eventually I'm going to make an auxiliary tank for mine too but I'm doing mine where my nitrous bottle resides between the factory tank and the tire but I'm extended 3". I'm going to make it removable so I can run the aux tank on the street and when I go to the track I can remove it and remount my bottle, I never usually ride around on the street with the bottle in there anyway. I'm going to keep it the same height as the factory tank and just vent it but no filler neck (can't figure out a place to put one) because it should fill with the factory tank, it'll take extra time to fill up but worst case scenario if I'm in a hurry I'll still have a little more than stock. I drilled out my drain bolt hole and tapped it to 1/8"npt for the take off for my nitrous fuel pump, I'll enlarge it to 1/4" and keep my shutoff valve on there I use to drain fuel now (I run pump gas on motor but race gas on spray and there's less waste this way) that way when I put on the other tank I can just connect the line to the aux tank to my drain line and turn it on but I'll have to pump gas on the slowest setting to let as much fuel as possible crossover to fill the aux tank. In the pics I hadn't installed the fuel line quick drain yet but hopefully you get the idea of what I'm talking about.

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