So, if suspension flex changes the chain tightness, and rider weight affect suspension flex, how does suspension sag not affect the chain slack? Help me understand.
Once your chain-slack is set, and everything tightened up, the slack will change from what you've set, EITHER by adding weight to the bike (YOU!), or by rear wheel suspension travel - LOOSE, TIGHTEST, LOOSE - as it is unloaded-on-the-stand; the 3 centers inline; and rear shock fully compressed. Hope I explained that clearly.
I'm probaly off kilter because I'm 20 miles from my bike...but.
I THINK that the chain is at the tightest point of the swing arm travel cycle when on the stand
(relative the the three cls involved) so that when the arm goes above or below that point the slack would increase slightly rather than get tighter.
Just my guess based on a failing memory set
the tightest point would be at the point where all three centerlines (counter shaft, arm pivot, & rear sprocket) are in a straight line with each other.
above & below that point the rear sprocket gets closer to the counter shaft.
since it's a pita to achieve the straight line situation you have to pick a point and come up with a number. the real world has little concern for ideal situations, especially mine
If you feel the need to REALLY understand this, find a way to remove the rear shock (obviously you'll need to support your Versys!), and then, using a tie-down or something similar, ratchet the swingarm UP till the THREE centers (countershaft, swingarm pivot, and rear axle) are ALL inline. At this point adjust your chain till it's tight but not overly tight.
Now let the swingarm DOWN till the distance between the shock-mounting bolt holes equals the length of your shock and MEASURE the slack again.
Now ratchet the swingarm UP till that distance equals the fully COMPRESSED length of your shock, and again MEASURE the slack.
The figure you will end up with will be SLIGHTLY less than the 1" figure Ma Kawasaki gave us as chain-slack at the tight end, and what I've detailed is the method by which she came up with... 1 to 1.4" slack.
The movement of the chain and sprockets, over that arc, is the ONLY thing that changes your chain-slack (unless you are SO HEAVY that your weight bends the frame or swingarm..., and in THAT case you'd be WAY-Y-Y over the max. weight allowed)!