Cruiser style bike, gas tank

[KanesKustoms]

Tank

i4Tas

I am working the very thing your asking about
I am building an aluminium tank that will fit into the horn tank. The place where the horn button will be the filler hole. The tank will only hold 1 qt of fuel but Im not going for distance its the look I want.
Two inch aluminium tube with end caps welded on each end two bungs
the screwcap of a coleman lantern for the gas cap lots of welding involved
Ive got 4 hours of time in the tank if I had to make one of these for someone it would be around 200 bucks just labor

Chris

 

[Dadkins1]

RC model boaters often use a IV bag in the floor of their boats - fits almost any shape - lots of sizes available.

 

[HoughMade]

I would suggest taking the tank sides off and brazing or welding it to seal it. I'm sure sheetmetal plates would have to be fabricated to fill in places. Add a neck (brazed or welded- I prefer brazing) and a place to mount a petcock and be done with it.