Aux tank install


Premier Member
Good Day Ladies and Gents,

I am in the middle of an Aux tank install and want some confirmation I’m on the right track.

Bike is a Vstrom 650, tank is a 19L fuel cell.

Plan is to run via AN-8 sized fuel line via an on/off valve. Having an AN male fitting welded to under side of tank. All gravity fed. Tank is grounded to frame. Rollover breather will be fitted to prevent spillage in the case of a drop.

Anything I am missing or should consider?

Kind regards,



Premier Member
So far so good Tadge.
Two questions from looking at your pics.
Why do you have that extra 50mm of bright ali shs between the tank and the lower black/frame?
Can you post up a pic of your planned entry point into the main tank or fuel circuit.
Its a nice looking tank. The second pic leads me to think the tank can be mounted lower.
What side of the bike is your tap outlet Tadge?


Premier Member
What is your estimated range once this is running Tadge.
Bloomin great addition to any bike. So good for just knowing you can get your head down for a nap and not stress in the middle of the night to get your fuel stop before they close. You will love the addition mate.


Premier Member
That looks like the same tank that I have on the F6 so assume that the extra height is to clear the sump at the front.
The only other thing I would do is fit a set of quick disconnects in the line,looking at your pic I'm guessing the tap will be on a right angle bend coming out of the tank just above the seat? So put them between there and the bike tank.
The quick disconnects make it much easier to get the tank off for what ever reason. Available at your local BMW parts dealer for about 100 bucks
much less expensive than Earls and the like.

apologies for the ordinary pic.


Premier Member
Good Day all,

Vlad, yes it looks like the same tank. Good call on the quick disconnects, I’ll have a chat with the BMW shop.

Gatey, the estimated range will be 850km when both full so I’ll have a VERY comfortable 600km range in all conditions. The tank is lifted as there is a sump underneath for the outlets. Tap will be on the LHS with lines running down the side of the bike entering under the seat. I’ll get a pic of the main tank entry point, this is a weld in male AN-8 fitting. I have had a lot of trouble finding someone to weld it, however I have finally found someone willing to do it. There is a plate underneath the main tank that comes out to remove the fuel pump so this will provide good access to wash and dry the tank prior to welding.

Breather will be a line exiting near the number plate with a roll over valve.

Depending on the welder availability, I’m hoping to have it all plumbed and running early next week.


Brendon Tadgell


Premier Member
Gday Brendan.
I had totally forgotten about the stock sump on those tanks. I do remember now.
Here is a link you may have already found from Ox34 a few years back.

Can I suggest a pig tail loop for the vent line. Out of the tank before it descends to the back of te bike.
Also I strongly recommend you visit you local boat shop and but fuel quick connects of them. They are made for boats, male and female and Stainless steel to boot not plastic. A set will cost under $50. Suzuki, Chrysler or Marlin all kits will adapt to AN 8 or An 6

This is a great place to get your bits. I place an order through work with these guys at least once a month.

Dont be fobbed off buy guys expressing difficulty or reluctance welding or adapting on fuel tanks Brendan. Its not rocket science but welders will make out like its such a big deal.
If you flush your tank with water use Metho to absorb the water afterwards. Most bikes have a large enough hole at the pump location to get your hand inside the tank to wipe it dry with a cloth. Just be careful of the sharp edges as a cut to the wrist is easily had.

Thats a nice range regardless off the 600k rule. Remember 600k require only getting a docket not fuel. Its there to get you off the bike is all. Nice to know an ATM might well be available when fuel is well further down the road.
Well done with your project thus far Brendan.


Premier Member
Some sound advice by Gatey, he knows his tanks, the snap connector, pigtail and Speedflow connectors are a breeze to work with :)