2017 Kawasaki Z 125 PRO — Owner's Manual
Drive Chain Slack Inspection Set the motorcycle up on its side stand. Clean the chain if it is dirty, and lubricate it if it appears dry. Rotate the rear wheel to find the position where the chain is tightest, and measure the maximum chain slack by pulling up and pushing down the chain midway between the engine sprocket and rear wheel sprocket. If the drive chain is too tight or too loose, adjust it so that the chain slack is within the standard value.
Drive Chain Slack Adjustment. Remove the cotter pin, and loosen the axle nut. Loosen the left and right chain adjuster locknuts. If the chain is too loose, turn in the left and right chain adjusting nuts evenly.
If the chain is too tight, turn out the left and right chain adjusting nuts evenly. Turn both chain adjusting nuts evenly until the drive chain has the correct amount of slack. To keep the chain and wheel properly aligned, the notch on the left wheel alignment indicator should align with the same swingarm mark that the right wheel alignment indicator notch aligns with.