Im by no means dawging his idea...let me rephrase what I said...It looks like more work than what "I" would want to go through...and Pete thats a good idea...never thought of that.
Excuse my art work. I meant to chop off the top of the fuel tank, and then possibly have the filler cap under the seat. no cutting of plastic so it still looks good and easy enough to get at to still refuel.
It looks like if you chopped off the stock filler neck and sealed that up it would work. You would obviously need to install a new fillerneck elsewhere and would lose some of the capacity. Doable, but surely a decent amount of modification to the stock tank.
Definitely gonna have to do some fuel tank mods...cuz I dont even think the seat is gonna fit on there right...tank will be in the way...the YFZ seat gets real narrow toward the gas cap...a lot narrower than the dales.
Looks to me like it's going to need a new tank. If you relocated the filler, it could only go lower limiting the amount of gas in the tank since you obviously can't fill it above the filler. An aluminum tank with similar to stock but more slope wouldn't be too hard to make- if you're a fabricator.
I'm going to have to change my mind about cutting the plastic. You can make a new aluminum tank and have the filler neck come out where it is supposed to which would give you the same or more capacity. And an added bonus is that you make 1 tank modification for the life of the quad, or you can mod every tank cover you will ever buy for it. Which will probably be only one unless you change colors.
Only negative to a aluminum tank is they crack eventually.Might be a long time or might be right away but to prevent cracks you end up with a tank heavier than stock plastic.