How to Tune a Kawasaki Jet Ski


Kawasaki Motors Corporation began as a motorcycle company and entered the personal watercraft market in 1973 with its first stand-up Jet Ski. In 2011, the company still offered Jet Ski watercraft, engineered for one to three passengers to sit or stand and ride the waves in comfort. Like most vehicles, Kawasaki Jet Skis require regular maintenance in order to continue to run most efficiently. The company offers similar tune-up instructions in all Jet Ski owner's manuals, including instructions on how to inspect and tune the spark plugs, how to flush the cooling system, and how to clean and charge the battery.

Things You'll Need

  • Standard wrench
  • Spark plug wrench
  • Spark plug gap tool
  • Replacement spark plugs
  • Garden hose with fresh water hookup
  • Baking soda and fresh water
  • Shop rag
  • Wire-bristle brush
  • Separately-powered battery charger
  • Waterproof grease

Spark Plugs

  • Lift the handle pole and unscrew the engine hood to access the Jet Ski's engine. Each spark plug can be found inside each of the engine's cylinders. The number of spark plugs and the type varies according to Jet Ski model, as listed in the "Maintenance" section of the owner's manual.

  • Remove the spark plug cap for each cylinder.

  • Rotate each spark plug counterclockwise with a spark plug wrench and lift each spark plug out of its cylinder.

  • Inspect the electrode end of each plug. Replace the spark plug with the type specified in the owner's manual if it is burnt, white and brittle, or black and charred.

  • Measure the spark plug gap, which is the distance between the hook at the end of the plug. This gap should measure the distance specified in the owner's manual for that Jet Ski.

  • Shorten the spark plug gap by pressing the hook-end of the plug against a flat, firm surface if the gap is too wide.

  • Widen the gap by pulling the hook-end wider with a spark plug gap tool if the gap is too narrow.

  • Reinstall each spark plug in its respective cylinder by rotating it clockwise into its hole with the spark plug wrench. Return the spark plug caps to each plug.

Cooling System

  • Raise the handle pole and hook the stopper pin to the rest to keep it upright while tuning the cooling system.

  • Remove the engine hood.

  • Remove the cooling inlet fitting cap, located at the base of the now-upright handle pole.

  • Attach a garden hose with a screw-in fitting at its mouth to this inlet. Do not turn the hose's water on yet.

  • Start the engine and allow it to idle.

  • Turn on the water for the hose immediately, adjusting the flow so that a slow trickle comes out of the bypass outlet on the port side of the hull.

  • Allow the engine to idle for several minutes with the water running, allowing the clean water to flush away any debris or maritime buildup from the cooling system.

  • Turn off the water and keep the engine idling.

  • Rev the engine a few times to clear any excess water out of the exhaust system.

  • Remove the hose and screw the inlet filling cap back in place.

Battery Tune-up and Charge

  • Access the battery by raising the handle pole and removing the engine hood with a standard wrench. Dismantle and remove the air intake cover for better access to the battery.

  • Disconnect the black (negative) lead from the sealed battery first, then disconnect the red (positive) lead.

  • Undo the two rubber battery hold-down straps.

  • Lift the battery from the hull.

  • Clean debris from the top of the terminal with a solution of one tablespoon baking soda and one cup of water.

  • Scrape away any corrosion or caked-on debris with a wire-bristle brush. Rinse the top with fresh water and dry it with a clean shop rag.

  • Inspect the battery for any sign of damage including cracks and worn terminals. Replace the battery with the same type listed in the "Specifications" section of the owner's manual if damage is found.

  • Charge the battery fully with a separate battery-charging device. Kawasaki recommends the Battery Mate 150-9, Christie C10122S, and OptiMate PRO 4-S/PRO-S chargers.

  • Reinstall the battery by reversing the removal steps listed above. Be sure to connect the positive (red) lead first and the black (negative) lead second and to secure the battery hold-down straps.

  • Tighten all battery terminals and coat them in waterproof grease to prevent corrosion.

  • Reassemble the air intake cover and return the engine hood.

Tips & Warnings

  • Follow the maintenance guide in the "Maintenance" section of the owner's manual to see how frequently tune-ups are recommended for a particular Jet Ski.
  • Batteries can release explosive fumes or acid. Always wear gloves and goggles while tuning the battery and never smoke or work near an open flame while working on this system.
  • Only use the spark plugs recommended in a particular Jet Ski's owner's manual to avoid serious engine damage.


  • Photo Credit jet-ski 1 image by Melisback from
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