Yamaha 2 Stroke Outboard 100 Hour Service Maintenance Kits

Yamaha 2-Stroke Marine Engine 100-Hour Service Maintenance Kits Resources and Information 

Each Yamaha 2 Stroke Outboard 100 Hour Service Maintenance kit contains all you need for proper Yamaha-directed 100-hour service. Kits include products such as: Yamalube oil, Yamaha outboard fuel filter, Yamalube marine gear lube, Yamaha outboard lower unit drain gaskets, Yamaha fuel filter elements, and NGK spark plugs. 

We stock a complete range of Yamaha outboard parts, and service kits to help you service your specific 2-stroke Yamaha outboard model, including: 

• Yamaha 9.9 2-Stroke Outboard 100-Hour Service Kit
• Yamaha 15 2-Stroke Outboard 100-Hour Service Kit
• Yamaha 25 2-Stroke Outboard 100 Hour Service Kit
• Yamaha 30 2-Stroke Outboard 100 Hour Service Kit
• Yamaha 50 2-Stroke Outboard 100 Hour Service Kit
• Yamaha 60 2-Stroke Outboard 100-Hour Service Kit

We also regularly release new helpful resources like: 

• Yamaha Outboard Specs & Capacities Chart
• Yamaha Outboard Engine Schematics
• Yamaha Outboard 100-hour Service Guides

Yamaha 2-Stroke Outboard 100-Hour Service Maintenance Kits FAQs

How do I change my Yamaha 2-stroke outboard engine oil?

If your two-stroke Yamaha outboard has oil injection with a remote oil tank inside the boat, you will begin your service by accessing this tank. These remote tanks are not always situated in the easiest-to-reach places, so you may have to consider removing a livewell tub, cooler, or access panel to get to the tank. Loosen the tank from its bracket and locate the oil supply hose that comes from the pump on the tank and heads toward the engine. You should notice a small, white, inline filter that strains the two-stroke oil in route to the engine. This small filter is often overlooked, but without a steady supply of Yamalube two-stroke oil, your engine will quickly go into reduction mode, or worse. Cut the small zip ties that secure the oil line to the strainer and replace the strainer quickly before you drain oil all over the bilge. This process is a little messy, so a few petroleum sorbent pads can help avoid a mess. Having some good quality nitrile gloves on board the boat or around for your service is also a great idea.

With the tank loosened from its bracket, it is a great time to use a small service flashlight to illuminate the bottom corners of the tank. The clear plastic will allow you to spot any debris or water deposits accumulated inside the tank. If found, you will need to remove the tank, drain, and clean. Debris is most often introduced from fill caps being left open, damaged fill cap o-rings, or dirty containers used to purchase bulk oil.

When complete, reinstall the tank into the bracket and remove the cowling from your engine. Use the manual transfer switch on the side of the engine to verify oil is flowing through your new filter and the system is primed. Your Yamaha 2-stroke oil maintenance is now complete. You are ready to begin your engine service.

How do I service my Yamaha outboard fuel system?

Yamaha fuel system maintenance is a critical aspect of 100-hour service. Depending on your application and style of boat, you likely have a fuel-water separating filter aboard your vessel. If you have not seen one, simply follow the routing of your fuel hose from the engine rigging tube backward through the boat. These vary in shape and manufacturer, so be sure to order the identical replacement filter. Use a filter wrench to loosen the existing filter element and use caution when removing it as it will be filled with gasoline.

A clear plastic or glass container is helpful to dump the filter into and to examine the contents. A small amount of debris is common, as is a small amount of water after the fuel has had a moment to settle. Larger amounts of water would warrant further investigation. If your filter’s mounting location allows it, pre-fill the replacement filter with some gasoline to make re-priming the fuel system easier later. It is also advisable to use a small amount of grease to lubricate the o-ring prior to installation. Spin on and hand tighten only about a half turn to snug.

Continue your Yamaha fuel system maintenance by moving back to the engine and locate the filter element in the clear plastic bowl on the front of your block. Depending on your engine model, this filter cup may be removed by using a special cup wrench – or standard tools and a little caution. If applicable, unplug the water-in-fuel sensor and spin the cup off the housing. Again, drain into your clear container and examine the fuel. If your main water separator was free from water, this filter should be as well. Inspect the o-ring on the top of the filter cup and lightly grease for ease of installation or replace if needed. Replace the filter element with a fresh one and reinstall the cup. Use the cup wrench to tighten. Locate your engine’s primer bulb and use the primer to pump up the fuel system. You should observe gasoline entering and filling the filter cup. Check for leaks and prime until the bulb becomes firm. As a tip, primer bulbs work best when the arrow points up, so use any extra hose in the line to help you tilt the bulb vertical.

If you are not running Yamalube Ring Free on a constant basis, the 100-hour service interval is a great time for a “shock treatment.” Ring Free is a fuel system conditioner that also helps to remove carbon deposits. A standard dose is 1 oz per 10 gallons, but if you are not running the product all the time, you can double that ratio for more cleaning power. Simply pour the Ring Free into the fuel tank fill and go run the boat – no additional work is needed. It is advisable to inspect your fuel tank fill’s o-ring for damage when you add Ring Free as a damaged o-ring can allow water from rain or boat washing into your fuel system.

If you will be storing your boat for the season after service is performed, and liberal application of Yamaha’s STOR-RITE Fogging Oil and the addition of Yamalube Fuel Stabilizer & Conditioner Plus is highly recommended.

Why keep my Yamaha outboard lower unit gears lubricated?

The gears inside your Yamaha lower unit are constantly turning, and the only protection they have is the lower unit lubricant you use. Its job is to form a micro-thin film between the metal component parts to keep them from actually touching. Under the large loads, these gears exert, proper lubrication requires extreme resistance to pressure, foaming, and molecular shear. And, since the lower unit operates underwater, its lubricant also has to be capable of maintaining necessary lubricity even when a significant amount of water is present, should some leak inside. Ordinary gear lubricant can’t do all of this; so always avoid automotive or tractor gear oils. Use a quality, marine-based formula, like Yamalube Marine Gearcase Lube. It can perform all of these required protection and lubrication duties, even with a full 10% of water present. There’s even an HD formula, to meet the special needs of Yamaha’s top-of-the-line V MAX SHO, 4.2L V6 Offshore, and 5.3L F350 V8 outboard lower units.

How do I change my Yamaha lower unit gear lubrication?

Yamaha recommends replacing your lower unit lubricant after the first 20 hours for a new outboard, then every 100 hours after that. Also, if it’s milky in color or smells or looks burnt when you’re checking it, it’s time for a change. To do it yourself, place a pan under the bottom drain screw, remove the screw, and then remove the upper vent screw on the side of the lower unit. Allow all of the lubricant to drain into the pan. While you’re waiting, check the drain screw. Also at this time, replace the small crush washer present on each screw (commonly known as “drain plug gaskets”). If you don’t see one, it may still be adhering to the outboard. Use a pick to pull it free, as these must be located, discarded, and replaced each time these screws are removed.

Once all the lube has drained, refill the lower unit by threading the appropriate fitting into the lower unit drain screw opening (on the bottom of the bullet) and slowly pumping in fresh Yamalube Marine Gearcase Lube or Lubricant HD. Once you see this new fluid seeping out of the upper vent screw hole, stop and wait 5 minutes, then very slowly continue pumping until it seeps from the vent screw again. At this point, replace the vent screw with a new crush washer installed, and tighten it according to manufacturer specifications. Remove the fitting attached to the drain screw opening, and quickly re-install the drain screw with the new crush washer installed. Tighten to factory specifications.