Winterizing A Yamaha Twin Engine Jet Boat: Step-By-Step Guide

Winterizing a Yamaha twin-engine jet boat is essential to protect the engine from cold weather damage. While the process is not as complex as winterizing other boats, it is still necessary to prevent water in the engine from freezing and expanding, which can lead to engine block or exhaust destruction. Here are the key steps to winterize your Yamaha twin-engine jet boat effectively:

Fuel treatment to prevent gum formation

To prevent gum formation in your Yamaha twin-engine jet boat's fuel system, you must treat the fuel before storing the boat for winter. This is especially important if you live in a cold climate and plan to store the boat for an extended period.

The first step is to add a fuel treatment product, such as Sta-Bil, to your fuel during the boat's last outing of the season. Run the engines for a considerable amount of time to ensure the fuel treatment is distributed throughout the fuel system. Simply adding the treatment to the tank is not enough.

On your way back from your last outing, top off the fuel tank to prevent condensation from forming during storage. Don't forget to add a fuel stabilizer to the fuel used for topping up the tank. This will help prevent gum formation and keep your fuel system in good condition during the boat's hibernation.

If you have a short lay-up period of around three months or less, you may not need to worry as much about fuel treatment. However, it is still a good idea to take some preventive measures, especially if you live in an area with freezing temperatures.

In addition to fuel treatment, you can also use fogging oil to protect the internal parts of your engines from corrosion. This will help prepare your engines for storage and prevent any damage caused by condensation or moisture buildup.

By following these steps and treating your fuel properly, you can effectively prevent gum formation in your Yamaha twin-engine jet boat's fuel system during the winter season.

Flushing the cooling system

Here's a step-by-step guide on how to flush the cooling system:

• Ensure your boat is out of the water and horizontal (level) with the ground.
• Locate the flush port. This could be on the transom (back of the hull), under a seat, or in the engine compartment. Refer to your owner's manual if you're unsure.
• Attach a garden hose to the flush fitting, but do not turn on the water flow yet.
• Start the engine and let it idle.
• Now, turn on the water flow through the hose.
• Follow the instructions in your owner's manual for idling time, typically between 90 seconds to 3 minutes.
• Turn off the water flow and then shut down the engine.
• Disconnect the water hose and replace the cap over the flush fitting.
• You can also rinse the jet drive by spraying water into the inlet at the bottom of the hull and into the jet nozzle at the back of the boat.
• Remember to always turn off the water flow before shutting down the engine to avoid water entering the cylinders through the exhaust system.

Additionally, if you operate your boat in saltwater or silty/sandy freshwater conditions, it is recommended to flush the engine cooling system after each day of operation. This will help prevent corrosion and keep the cooling passages clear.

For long-term storage in cold climates, you may also want to consider using RV or marine antifreeze in your cooling system. This will provide additional protection against freezing temperatures. Simply follow the same steps as above, but use antifreeze instead of water. Make sure to use propylene glycol-based antifreeze, which is less toxic to animals than ethylene glycol.

Finally, don't forget to properly maintain your boat throughout the year. This includes regular flushing, treating your fuel, and keeping the engine and compartments clean and dry. By taking these steps, you'll ensure your Yamaha twin-engine jet boat is ready for winter and will perform reliably when you take it out on the water again in the spring.

Fogging the engine

Before you begin, ensure you have the necessary items, including an aerosol can of fogging oil, such as STA-BIL or Yamaha Stor-Rite, and the engine's normal lubricants.

Step 1: Start the Engine and Remove the Air Filter

Start by turning on the engine and removing the air filter. This will allow for better access to the engine components during the fogging process.

Step 2: Spray Fogging Oil into the Air Intake

With the engine running, spray the fogging oil into the air intake of each cylinder. This step should be done carefully and in a well-ventilated area to avoid any potential hazards.

Step 3: Shut Off the Engine

After spraying the fogging oil, allow the engine to run for about 10 seconds, and then shut it off. This will give the fogging oil time to coat the internal surfaces and provide protection.

Step 4: Remove and Treat Spark Plugs

Remove the spark plugs carefully. You can then choose to treat them with fogging oil by spraying into each cylinder for a few seconds. This step will help protect the spark plugs from corrosion and ensure they remain in good condition during storage.

Step 5: Reinstall the Spark Plugs

Once you have treated the spark plugs, carefully reinstall them. It is important to ensure they are securely fastened to avoid any issues when you start the engine again in the spring.

Step 6: Optional Bonus Step

As an optional step, you may want to consider treating other engine components with fogging oil. This can include spraying fogging oil into the carburetor before the engine runs out of fuel or into the air intake of an outboard motor just before it starves out of fuel.

Removing the batteries

To remove the batteries, first, remove the negative terminal, then the positive. Take the battery out and check the posts and terminals for corrosion. If there is any corrosion, clean them using a stiff-bristled brush and a battery cleaner. Some people use Coca-Cola for this step, as it is acidic. Once clean, coat the terminals with grease to prevent corrosion.

Next, check the battery for any problems, such as cracks in the casing or a low water level. If the battery is in good condition, it is ready to be stored for the winter. Place it on a rubberized surface in case of any drainage. You can also put a trickle charger on it periodically so it does not lose its charge.

It is also important to note that, while the boat is in storage, the battery should be stored somewhere warm, like a garage, and kept in a well-ventilated area. Additionally, it is recommended to keep the battery active by using a smart battery charger or a solar charger.

Cleaning and covering the boat

Before you put your boat away for the winter, it's important to give it a thorough clean. You might consider waxing the finish and treating the upholstery with a product like ArmorAll. Apply lubricant to the control cables where they connect to the jet nozzles and lubricate the nozzle pivot points.

Prop open any doors and hatches to allow air to circulate and reduce mildew buildup. If you can, store the boat with the wheels off the ground and cover the tyres to prevent damage from UV radiation.

When it comes to covering the boat, do not use an impermeable tarp as this will trap moisture and may damage the vinyl upholstery. The boat needs to breathe to reduce mildew buildup. Prop up the cover so it doesn't collect water if the boat is stored outdoors.

If you're storing the boat outside, it's worth getting a cover for your cover. A second cover or a tarp will provide extra protection from the elements. This will help to keep your boat clean and prevent bugs and animals from getting in.

Frequently asked questions