Kawasaki zephyr rpm error. idles at 1,000 but shows 3,500 rpm. sometime goes back what it should be. what is the problem ? let you know my motorcycle is not 750. its Zephyr 550, couldnt find the 550 model in the link. thanks

sounds like you have a vacuum leak. that is where i would start. other then that i would start checking sensors.

Try this:
Turn kill switch to ON/RUN position.Cycle the ignition(key) switch 4 times (each time long enough for engine light to go out ~15 seconds).
This resets the "zero" position of the Throttle for the ECM.

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Please the air fuel ratio.

Contact your local kawasaki dealer .they may have a current price listing for your make of bike ,unfortunatly ,as the bike is nearly 20 years old they may not have a listing of what its worth .The price will be very low so don't get too excited in having a lot of cash back for it ..

got air in the cooling system

The carbs have some very tiny passages that will easily be blocked by that varnish reside. You will need to pull the carbs and flush every jet drilling with an aerosol carb cleaner like gumout Remove the jet and blow the spray cleaner through, rinsing out ant gum build up. Clean all the passages you can find and the rest of the carb linkage and bod. Idle passages are vacuum drawn and if your manifold vacumm is low then the fuel cannot be sypyphoned. to keep the engine running. Vacuum leaks are common on bikes that sit because the hoses dry up and loose thier seal. Check all you hoses and replace any in doubt. Good luc And let me know, please.- Ned

Here ya go!

Cylinder numbering method Left to right, 1-2-3-4 Firing order 1-2-4-3 Ignition timing From 10° BTDC @ 1,000 rpm to 40° BTDC @ 3,400 rpm Spark plugs NGK B8ES or ND W24ES-U