I recommend ratchet straps and a long imaginary line through the bike.
Use the ratchet straps to compress the rear suspension until your imaginary line looks straight from your back axle through the countershaft forward. You'll have to pick a reference point forward on the engine to use as your third point; and a yardstick or piece of pipe might help you "draw" your imaginary line. Stop ratcheting when all 3 points make a straight line.
This is when your chain is at its tightest point.
Oh yeah, forgot to mention: this is probably easier on a bike with a cyclerack. If not, you can still strap from the swingarm to the subframe under the seat, it'll just be more annoying.
I think it accomplishes lizrdbrth's anal method without the joys of removing the shock, though. I will feel free to stand by, corrected, if I'm wrong
For what its worth, I usually roll the bike back and forth and bounce on the suspension (or have someone else do it) after I adjust to confirm everything "feels" right with the chain tension.
Use the ratchet straps to compress the rear suspension until your imaginary line looks straight from your back axle through the countershaft forward. You'll have to pick a reference point forward on the engine to use as your third point; and a yardstick or piece of pipe might help you "draw" your imaginary line. Stop ratcheting when all 3 points make a straight line.
This is when your chain is at its tightest point.
Oh yeah, forgot to mention: this is probably easier on a bike with a cyclerack. If not, you can still strap from the swingarm to the subframe under the seat, it'll just be more annoying.
I think it accomplishes lizrdbrth's anal method without the joys of removing the shock, though. I will feel free to stand by, corrected, if I'm wrong

For what its worth, I usually roll the bike back and forth and bounce on the suspension (or have someone else do it) after I adjust to confirm everything "feels" right with the chain tension.