2017 Kawasaki KX450F — Owner's Manual
A brief break-in procedure must be carried out to obtain the proper operating clearances in the engine and transmission, which are necessary for performance and reliability. Break in the engine as follows. Start the engine and let it idle until it is thoroughly warmed up. Ride the motorcycle for about 20 minutes within 1/2 throttle opening.
Stop and let the engine cool completely. Be sure to check the tightness of nuts and bolts, oil leakage, coolant leakage and any irregularities. Start the engine and ride the motorcycle for about 40 minutes within 3/4 throttle opening. Stop and let the engine cool completely.
Be sure to fully check the tightness of nuts and bolts, oil leakage, and any irregularities, especially, each cable elongation, brake play, chain slack and spoke tightness. Change the engine oil, oil filter and front fork/rear shock absorber oil to the new one. After the break-in procedure has been properly carried out, the motorcycle is ready for regular operation. Using the proper riding skills and techniques and avoiding recklessly high engine speeds will keep the engine trouble-free.