2 stroke outboards

Types of 2 stroke outboards

2-stroke outboard motors are often referred to as two-cycle engines. They burn fuel and use a two-part cycle of stroke to complete one full revolution of the crankshaft. The engine has a combustion chamber where the piston moves up and down, completing two strokes with every crankshaft rotation. The first stroke happens when the piston rises in the cylinder. This action creates a vacuum that forces the air-fuel mixture into the cylinder from the ports and exhausts the remaining combustion gases. The second stroke occurs when the piston moves down in the cylinder, compressing the air-fuel mixture in the chamber and triggering ignition from the spark plug. The cycle then repeats. Many marine engines use 2-stroke outboard motors because they are lightweight and powerful.

Below are the different types of 2-stroke outboard motors:

• High-speed engines: These engines have a high crankshaft rotation speed. They create a high-frequency sound that is unpleasant to the human ear. The sound level falls under the category of noise that can cause hearing damage. The noise level is above 85dB. Because of the high noise level, these engines use a sound dampening mechanism to reduce the sound to a safe level.
• Medium-speed engines: These engines have a moderate level of noise and sound to the human ear. The sound level ranges between 50-80dB. These engines don't have sound dampening mechanisms. The noise level can cause discomfort but doesn't cause hearing damage.
• Low-speed engines: These engines have a low sound level that is bearable to the human ear. The sound level is below 50dB. These engine sounds are comparable to normal conversation or ambient noise. There is no need for sound dampening mechanisms as the sound generated is tolerable.

Specifications and Maintenance of 2-Stroke Outboards

Here's a look at specifications and maintenance of 2-stroke outboards

Specifications of 2-stroke outboard motors

• Engine size:

  Engine size is an important specification when considering buying a 2-stroke outboard engine. The size of the engine indicates the power that will be generated by the motor. A larger engine size means that more power will be produced. More power means that boats will attain higher speeds, and larger boats can be accommodated. A large engine size enables the outboard motor to be used in more applications. The engine size for 2-stroke outboard motors ranges from 2 to 500 HP.

• Weight:

  The weight of a 2-stroke outboard motor is an important specification that needs to be considered. The weight of the motor will affect the overall weight of the vessel. A 2-stroke outboard motor with a lower weight can be easily transported and mounted onto the boat. 2-stroke outboard motors weigh anywhere between 20 and 150 kg.

• Cooling system:

  The cooling system is an important specification to consider when looking at 2-stroke outboard motors. When the motor is being used, it is important that the temperature of the motor is maintained within the optimal operating range. If the temperature of the motor exceeds the optimal operating range, the motor will be damaged. The cooling system of 2-stroke outboard motors is either air or water-based.

• Starting system:

  The starting system is an important specification to be considered. 2-stroke outboard motors can either have a manual or electric starting system. A manual starting system is easier to use when the outboard motor is low in weight. A manual starting system is more affordable than an electric starting system.

• Fuel tank capacity:

  The fuel tank capacity of a 2-stroke outboard motor is an important specification to consider. The fuel tank capacity will determine the amount of time that the motor can be used before refueling is needed. A larger fuel tank capacity will allow the motor to be used for longer periods. The fuel tank capacity of 2-stroke outboard motors is around 10 to 100 liters.

Maintenance of 2-stroke outboard motors

• Regularly replacing the engine oil:

  When maintaining a 2-stroke outboard motor, it is important to regularly change the engine oil. The engine oil should be changed before and after the outboard motor is used. Changing the engine oil will help the motor run efficiently. The engine oil should be of high quality and suitable for the outboard motor.

• Cleaning the air filter:

  Another important maintenance tip for 2-stroke outboard motors is cleaning the air filter. The air filter should be cleaned at least once a week. A clean air filter allows for the efficient running of the outboard motor by ensuring that air flows freely to the engine.

• Inspecting the spark plug:

  It is important to regularly check the spark plug to inspect its condition. The spark plug should be changed if it is damaged or worn out. This should be done at least once a month. A healthy spark plug ensures that the outboard motor runs smoothly.

• Checking the fuel system:

  When maintaining a 2-stroke outboard motor, it is important to check the fuel system. The fuel system should be checked weekly to ensure that there are no leaks. The fuel lines and fuel filter should be inspected to ensure that the outboard motor runs efficiently.

How to Choose 2-Stroke Outboards

Choosing a suitable 2-stroke outboard engine requires careful consideration of several factors:

• Portability: For those who need to move their outboard motor frequently, such as on camping trips or among different boats, portability is essential. Lightweight and compact motors are easier to transport and handle. Consider the weight and dimensions of the engine, as well as any built-in handles or transport wheels that might facilitate movement.
• Fuel Efficiency: While 2-stroke engines are traditionally less fuel-efficient than their 4-stroke counterparts, advancements in technology have improved this aspect. For those who prioritize fuel efficiency, it's essential to investigate the specific fuel consumption rates of different models. Additionally, consider the fuel tank capacity, as a larger tank can provide extended range even if the engine consumes fuel at a higher rate.
• Start Mechanism: Outboard motors can be started manually or electrically. Manual start motors often have a recoil starter, similar to a lawnmower, which requires pulling a cord to start the engine. While these are generally more reliable and require no additional electrical components, they can be physically demanding, especially for larger engines. Electric start motors utilize a battery to turn the engine over, making starting much easier, particularly for extended use or by multiple users. However, electric start motors require a reliable battery system and sometimes additional maintenance.
• Weight: When choosing a 2-stroke outboard motor, considering the weight is essential. These engines are known for being compact and lightweight, making them suitable for various watercraft. Their reduced weight contributes to increased boat speed and fuel efficiency. However, when selecting a motor for a specific boat, users should consider the overall weight in relation to the vessel's size and design. An excessively heavy motor can affect a boat's performance and stability.
• Shifting Gear: Consider the gearing system of the motor. Some models offer forward/reverse gears, while others have a simple forward-only operation. Gearing with forward and reverse gears provides more control, especially in tight spaces or when docking. However, forward-only motors are usually simpler, lighter, and more affordable, making them ideal for basic fishing or leisure activities.

How to DIY and Replace 2-stroke outboards

Replacing a 2-stroke outboard motor can be a daunting task, but with the right tools and knowledge, it can be done. Here is a step-by-step guide on how to replace a 2-stroke outboard motor:

1. Choose the right replacement motor: Make sure the new motor is compatible with the boat and meets its requirements.

2. Disconnect the old motor: Use a wrench or socket to remove the bolts that hold the motor to the transom. Disconnect all electrical connections, including the battery. Disconnect all fuel connections, including the fuel tank and fuel lines.

3. Remove the old motor: Carefully lift the old motor off the transom and place it on a workbench or suitable surface.

4. Prepare the transom: Clean the transom where the new motor will be mounted. Inspect the transom for any damage and repair it if necessary.

5. Install the new motor: Carefully lower the new motor onto the transom and align it with the mounting holes. Secure the motor to the transom using bolts and nuts. Make sure the motor is aligned properly and at the correct height.

6. Reconnect all electrical connections, starting from the battery. Reconnect all fuel connections, ensuring there are no leaks.

7. Check the operation of the motor and make any necessary adjustments. Take the boat for a test drive to ensure everything is working correctly.

Replacing a 2-stroke outboard motor can be done by following these steps. It is important to read the owner's manual for specific instructions and safety precautions.

Q&A

Q1: Are 2-stroke outboard motors still available?

A1: Yes, 2-stroke outboard engines are still accessible, however, their accessibility might change relying upon the market and locale. Their creation has diminished because of stricter emanations guidelines and the ascent of cleaner and more productive 4-stroke motors.

Q2: How often should you service a 2-stroke outboard?

A2: Generally, a 2-stroke outboard should be serviced every 50-100 hours of operation or at least once a year, whichever comes first. However, the frequency can vary based on usage, environmental conditions, and wear and tear.

Q3: Can you run a 2-stroke outboard on diesel?

A3: No, 2-stroke outboard motors are designed to run on petrol, typically mixed with 2-stroke oil. Running on diesel is not feasible and can cause severe damage to the engine.

Q4: Are 2-stroke outboards more powerful than 4-stroke outboards?

A4: Yes, 2-stroke outboards are generally more powerful than 4-stroke outboards. They can produce more power for their size because they fire once every revolution of the crankshaft, compared to once every two revolutions in 4-stroke engines.