I remember now where I first encountered this claim that Honda had offered a large gas tank. It was an Ebay sale. That tank got bid up so high I was thinking WTF.
So here are the photos. The black tank that's missing the bottom edge trim strip and has silver spray paint on the top left of the tank is the big one.
BIG TANK in PHOTOS BELOW: silver spray paint in some areas on top, while the underside is in better-looking shape, and is turquoise in color
REGULAR SIZE TANK in PHOTOS: Black, but looks brown/rusty on the underside; and it has a silver trim strip on the bottom edge, and a stripe decal on the sides.
It's not aluminum -- it has rust on it (see the photos).
This is a Honda factory tank. It's 100% identical in every way to the stock tank except it's fatter.
I measured across the bottom of the standard tank at a point "A" on the middle of the underside -- 12".
I then measured across the same point "A" on the big tank -- 13 1/2".
Look at the details -- I took photos of both tanks in the same spots around the tank -- they're identical. If a fabricator/accessory parts maker was going to make a tank, he would NOT have the curves, dips and undulations in the exact same way -- on the UNDERNEATH side, where no one would ever see to compare and raise an objection about it 'not looking like a real cb750 tank' -- the big one has the same stamping details underneath as a normal-sized Honda factory cb750 tank.
The fact that the big tank has the exact same layout of dips, undulations, curves means it was stamped from an identical design, just enlarged a bit.
I'll try to find if I saved a copy of that Ebay sale from a few years back of that big tank. The listing said it was a Honda option. Then the bidders bid the piece of crap up to an insane amount.
Here's a photo comparison of one of the normal-sized CB750 tanks (black with an intact bottom-edge chrome trim piece) and the big tank (has a blotch of silver spray paint on top, and it doesn't have a chrome trim strip along the bottom edge).
The rear tank mount tabs are identical -- the rubber piece exactly fits both tanks.
This is not an aluminum tank -- rust spots here and there.
Underside, rear, of both tanks -- the turquoise one is the fat tank (no bottom edge chrome trim strip). Notice the crisscross pattern, identical.
Underside rear of the normal-size tank
THE FATTIE IS ON THE RIGHT HERE (big blotch of silver spray paint)
Measured the width at a point "A", the front end of the underside, on both tanks -- first here is the *normal* size tank -- it measured 12 1/2 inches across.
And the same measurement at point "A" on the fat boy is 14" wide.
Next, I measured the width at a point "B", the back end of the underneath of both tanks -- here is the *normal* size tank -- it measured 12 inches across.
The big tank, measured at the same point "B", is 13 1/2 inches wide:
Front frame mount points are identical (again, the blue-green tank is the fat boy)
Normal size tank's front frame mount:
Study the undulations, curves, details of the big tank (in turquoise) and the normal size CB750 tank (brown one) -- note also the metal clips that are spot-welded on the bottom at the edges, to clasp that bottom-edge chrome strip -- they're identical on the two tanks
Normal size tank
There you have it. I'm still searching to see if I saved that Ebay listing page of that curiously bid-up overpriced Cb750 tank. At that time I was buying a lot of CB750s and parts on Ebay. I saw a listing with a photo of a beat-up cb750 tank and though "nah, it's trashed" -- it looked awful. But the bidding was raising the price in a real shocking way. So I had to read the actual listing to figure out what was going on, and that's when I read the seller claiming Honda had a 'big tank' option in the early days of the CB750.
