hi my owners manual says adjust the chain tension with the bike on the side stand so weight is on the wheel, it also says tension should be 50-60 mm BUT you cant get this as the chain hits the swing arm at around 48 mm total movement. what I do is tension the chain gradualy until you just start to feel some resistance as you push the chain up against the swing arm. You wont be far off the recommended setting doing it this way. (this is with the wheel on the ground of course)

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XTz 660 tenere, adventure spec bash plate, main stand, skid marks tall screen, Oxford tail pack 36 litre. Kobra hand guards, Bigger cast footpegs, Zen overland luggage plate, USB power point, iridium spark plug, TKC80 f k60 R tyres, o2 and fuel Kev mods, DNA stage 2 filter. bark buster bar wieghts, Touratec side stand base and GPS mount. Led spot lights