Do you have to run high octane fuel in a Kawasaki kx 85cc?

No, you do not need to run high-octane fuel in a Kawasaki KX 85. This bike is designed to run on regular unleaded fuel, typically with an octane rating of 87. However, using higher octane fuel won't harm the engine and may provide slight performance benefits under certain conditions, but it's not necessary for optimal performance. Always refer to the owner's manual for specific fuel recommendations.