Increasing the horsepower on a Yamaha 40 HP outboard becomes difficult when you want to boost the horsepower by 10. Obtaining that much extra horsepower from a relatively small engine can also be costly. It may be less expensive to simply trade up to a 50 HP engine. However, with the right parts, you can increase the horsepower yourself.
Things You'll Need
- New larger carburetor
- New air intake and filter
- New exhaust system
Upgrade the carburetor. A higher-performance carburetor is one of the best ways to add horsepower. The carburetor combines air and fuel, which the engine then uses for combustion. This mixture is what gives the engine power. The more air and fuel that pass through the carburetor quickly, the more power the engine can deliver. The carburetor must match the size of the engine it will fit.
Upgrade the air intake system. Air is a key ingredient for performance. The more air an engine receives, the faster it can go. Restricted or limited air reduces performance. Upgrade the air intake system to a larger one that will let more air flow to the engine. Purchase a performance air filter. Air filters generally slow the flow of air to the engine. A performance filter allows more air to pass to the engine.
Upgrade the exhaust system. All the air that goes into the engine must also exit the engine. If the exhaust system cannot expel the used air quickly, it can back up and reduce engine performance. Manufacturers design stock exhaust systems on outboards to reduce noise and emissions. A performance exhaust system may be louder but it will also increase the horsepower of the engine.
Employ performance-enhancing fuel additives, special mixtures designed to increase the potency of the fuel. They can help increase performance and power. Make sure to use a mixture for a small marine engine. The right fuel additive can help the engine to run more efficiently.
- Small Outboards: Modifying and Converting Outboard Motors
- Land and Sea: tech talk
- "Yamaha, Mercury, & Mariner Outboards, All 4 Stroke Engines, 1995-2004 - Seloc Marine Manuals"; Seloc; 2005
- Photo Credit Jupiterimages/Photos.com/Getty Images
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