Modify/enlarge a metal fuel tank?

Anyone ever done it? I am working on a custom R1200RS project, and it may involve modifying a R1200R fuel tank because I want more capacity. I would think it can be enlarged by, in a sense, cutting off the top almost around the outermost edges, angling that portion up, and welding in metal to fill it back in. Given the thin metal of the tank, I'd assume it should be TIG welded to minimize heat/warppage.

Anyone ever try this or know someone who has had success with it?

Yes it can be done. The late Ray Randolph did it to many K75, K100 and K1100 aluminum tanks. The top was lifted, the back was reshaped and a new panel was inserted. It just takes good equipment, a good design, and a good welder (person).

You mean like THIS? Yep.

Old riding buddy and neighbor, Ray [Randoff - if you knew Ray, you know - ] Randolph in Lubbock did it on Oldwhatshernames R11R, along with a number of other modifications. We hated parting with that bike but she had to quit riding due to vision issues.

Wow, that R11R tank looks stock until you look closer and realize how much wider it has been modded.

If I go the route of modding an R12R tank, it would be to raise the front of the tank, with the "hinge" point to be right in front fo the seat. The tank top would be angled up and filled in. I like the shape of the R12R tank, but I've come so accustomed to the capacity of my 94 RS that anything less than six gallons of fuel seems not enough. A taller, but somewhat narrow tank may better suit my 07 RS project bike.

Another option would be to cut the top off and simply raise it up a couple of inches.