Motorcycle Repair: 1990 Ninja 600 is idling at 9k, ninja 600, screw adjustment

Question
Hi Mike,

My bike is idling seriously high at about 9k. I adjusted the throttle and it brought it down to 6k. I don't know what else to do. I do have a water pump leak, could that be the issue?

Answer
A leaking water pump is definitely a problem that needs to be fixed, but it has nothing to do with the idle speed. If adjusting the throttle cable reduced the rpm's a bit, I would check the routing of the cable itself to see if it is hung up somewhere. A sharp bend or kink will cause it to stick and keep the motor revving high. Also, check to see if there is a "cable splitter" somewhere along the length - this is a device that attaches two or more cables to the one coming from the throttle grip, sometimes the cable ends can pop out of it. Check the idle speed screw adjustment, it could be set too high. And check the operation of the carb throttle mechanisms, there could be damage or something interfering with them that would cause the throttle not to return to the proper idle.