Originally Posted by Norco John
You'd think Kawasaki and Harley-Davidson would build sprockets to tighter tolerances than the Happy Beaver Bike Motor and Medical Instrument Company, because I always had the same problem with my KZ and FLH, a slight difference in chain tension throughout the length.
The run-out on the sprocket is less than 1mm, both axially and radially.
Actually, it's NOT the sprockets at all. When you put a brand new chain on your
bike, motorcycle, or motor scooter, you will notice that the chain has the same
amount of up and down "play" in the middle of the chain no matter where it's
rotated. What causes the difference in the chain tension, is caused by the
stretching of the chain. Of course the stretching only occurs to the TOP portion
of the chain when you dump your clutch to start your motor, or in motorcycles,
when you pop your clutch to pull a wheelie or fast takeoff from a dead start.The
reason, is that the front engine sprocket is pulling the chain from only the top,
which of course, is connected to the upper portion of the rear sprocket. So all of
the force that is applied to that part of the chain slightly stretch's each link between the front and rear sprockets. Then it gets stretched even more at different locations over a period of time. This results in the uneven tension and
causes a lot of frustration when you try to adjust them.
In my 23 years as a motorcycle mechanic I've changed at least a hundred of them,if not more.