Hi
I had a tenere xt660z for 4 years. Now I have an Fj 09 2016. As per Yamaha official specification, both bikes weight almost the same with liquids (1kg difference). Yet when I ride the FJ09 feels lighter indeed than the tenere.
Yamaha has the wrong weight in one of the bikes?

Without actually researching the XT660z too much, it is more likely the center of gravity is lower on the FJ and the FJ has more power. Both can create the illusion the FJ weighs less until you put the bikes on an actual scale.

Without actually researching the XT660z too much, it is more likely the center of gravity is lower on the FJ and the FJ has more power. Both can create the illusion the FJ weighs less until you put the bikes on an actual scale.

Yep, concur with that. 

Regarding the weight ... 
 
I just went to the local quarry and asked to weigh my 1 week old FJ09.  Full of fuel, no bags and w/o me on it they told me 464lbs.  After my FJR's, ST1300 and Super Tenere ... heck even my VStrom it seems really light weight.  Putting it on the center stand is a breeze.

Full of fuel, no bags and w/o me on it they told me 464lbs. 

I came up with 484 on mine, with about 3/4 of a tank of fuel, with the factory saddlebags and rear rack (and likely a couple of quarts of Gatorade in the bags).   
So around 450 very dry, and something like 475 in typical on-the-road configuration seems about right.  
 

Sounds about right. I don't have bags ... yet.