I want to run a couple of wires for auxiliary lights to the battery, and want to fit them neatly (by my standards) along the frame under the tank.

Is it possible to just loosen the tank mounting fasteners and dislodge the tank upwards sufficiently to be able to get access underneath without disconnecting fuel lines and wiring?

Or do I need to stop faffing about and take the tank off properly!

There is a way...

take off the seat and the 'air scoop' (the plastic protection panel - dunno why they call then air scoops!) from the nearside of the bike (left as you sit on it).

You can see the frame running front to back.

Feed your cables from the underseat area towards the front of the bike, you should see it poking out under the tank. If it curls up inside then use a welding rod/stick/or something else that doesn't bend, tape the cables to the end of it and poke it through.

It can get a bit warm under there so I would advise you cover the cables, I used some of that curly cable tidy stuff from Maplin, then taped it up nice and neat. This way the cables are quite stiff and easy to feed through holes, gaps and the like.

You'll need to cable tie it to the frame every 6 inches (150mm) or so, but put one as close to under the tank as possible from both the underseat area and the front where it pokes out from under the tank - even thoug it's only a couple of inches apart in reality, it stops it from dangling about.

Or you could take the tank off, remove the air scoops, the two big bolts, the rear bolts, faff about with the vent and overflow pipes, unclip the fuel cable and electrics - Oh and don't forget to do this with an empty tank! ( this is why I decided to do it with the tank on!), a full tank is a nice light 23 kilo's.... and it's not well balanced for removal!

I found I can do just about any job without taking the tank off - brilliant piece of 'roadside repair friendly' design work I think.

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Never underestimate the power of stupid people in large groups.

Thanks, G.U.L.G: Excellent!

Good that I have decided to read the manual first and check on the forum. I am just in the middle of tank removal and was about to remove the fuel cables.... without emptying the tank! :-) In DL650 there is a valve, so you can easily disconnect the fuel pump, and no fuel will flow out.

No fuel comes out of the Tenere tank either, it's just b8stard heavy if you have it full.

OK, thanks. Manual said to drain the tank before removing it, so I figured out that it has no valve (which of course would be stupid). I have managed to install cables for GPS beneath the tank, without removing it. During the weekend I want to install heated grips, so probably will remove tank anyways, and then I will properly fix the cables to the frame.