OEM fuel tank of the DR is 13l of which 3l is reserve. Gives a range of 200km 'til reserve and 260km 'til dry.
Less if you go balls to the wall, into a howling headwind or through thick sand and muck. More, sometimes much more on dirt roads at 60kmh - 90kmh. (I managed more than 25km with a litre whilst riding with the missus & her Djebel 200)
We have Clarke tanks on our two DR650SE's.
They only hold 16l (13l plus 3l reserve) but have a number of advantages over all the other tanks:
The Clarke is the one and only which delivers true OEM part quality. It fits like a glove, the finish is flawlewss, it takes the automatic vacuum operated OEM fuel tap, does not restrict access to the engine and is removed just as quickly and easily as the OEM tank. Knee fit is perfect, the tank is sleek and narrow.
If it would come with two little steel tube spacers to fit the rear tank mounts it would be perfect. (Cut from 10mm x1.5 hydraulic pipe)
As mentioned it's only 16l which translates into 320kms until you're on the fumes. You'll hit the reserve after 260km.
Sufficient range with a little bit of planning here in SA.
Advantage: There is little slosh when it's half full.
Comparsion with advantages and disadvantages of the competitors:
IMS: You buy 3l of extra fuel with shoddier finish, a flimsy fuel tap (you have to trim the mounting hole in the tank and cut a bit off two ribs off the cylinder head if you want to use the OEM tap, recommended) and a brittle filler cap which unlike the Clarke does not use the "standard" cap thread making aftermarket purchases a bit more challenging. It's more expensive than the Clarke too and the need to buy a decent filler cap like a Tusk will add some 30US$ to the price tag. 380km 'til dry, 320km 'til reserve
The new Acerbis is - as usual - not famous for its finish. Italian tanks always came with poorly cleaned mould flash and this one does not make an exception. The fuel tap is as flimsy as the one supplied by IMS and the tap o-ring does not seal. Gotta love them Itailians
20l gives pretty much the same range as the IMS. Reserve seems to be a tad more (4l). Reserve after 320km, dry after 400km.
The Aqualine Safari - erm - is I'd say a bit cntroversial:
The fit is pathetic. Yo have to trim the tank mount rubbers else you won't get it onto the bike at all.
The aluminium cross brace looks as if someone welded it up next to the taxi rank in Khayelitsha. The way it attaches to the tank and braces against the frame show only the lack of a basic understanding of engineering principles. Nothing else. Expect to break stuff in a fall or redesign it.
IMHO a very poor product even more if you look at the atrocious pricing. Fuel slosh is a problem. An aprupt stop on a half full tank will have the bike rocking back and forth and the weight of 30l of juice don't make the ride handle like a mountain bike. Consider tank foam.
Tank removal for maintenance is a major mission.
Poor you if you need the range. Gravity feed will drain some 32l towards your carb giving you a range of 640km. Two taps give you two reserves. Can't remember when you hit reserve.