Honda's small engines are used in lawnmowers, generators and outboard motors. As with all engines, the small-engine 90 horsepower Honda outboard can be tweaked for maximum performance. A 90-HP outboard is on the larger end for outboard motors and generally used on power boats and professional sport fishing crafts. When attempting any repairs or motor upgrades, always be sure to read the user's manual before starting. Thorough knowledge of the engine will prevent amateur mistakes.
Maintain your Honda 90-HP regularly. This is the first and easiest step to ensuring a healthy motor. Failure to do so might rob the engine of power and also cause it to break down. Change the oil and gas regularly, and always perform seasonal maintenance when taking the engine in and out of storage.
Increase the air flow. Air is essential to the engine. Air flow into the engine must be unobstructed and air flow out of the engine must also be unobstructed. Check the air filter to make sure it is clean and free from debris. Check the exhaust system for any obstructions as well, and clean it if necessary. Replace the air filter with a larger one to increase the amount of air the engine receives. Replace the exhaust unit with a performance one. This will further help air flow through the engine.
Use fuel additives. First, a high-octane fuel should be used. Check the owner's manual for specific fuel types for the engine. Fuel additives are liquid mixtures that increase performance, functioning and efficiency of an engine. Simply mix the fuel additive into the fuel according the manufacturer's instructions.