if your talking about checking the tensioner yes.
if you do not have the little jig or do not want to waste a large amount of money you can measure the drop while in the bike like above but using a Dial Caliper
If the measurement is 16 mm or more then you need the spacer which is .390" diameter by .350" long. A 10 mm bolt shank is a good place to start.
Most important
Do not attempt to start, or roll the engine over in any way while the center nut is out of the tensioner!!!!!!!!!
It will jump time which is a bucket load of work as long as you do not damage the valves and pistons. If you do well its a lot more then a bucket of work