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Since its introduction, Suzuki’s flagship DF300 has been a showcase for Suzuki’s advanced technologies and designs. As the world’s first 220.7kW (300PS) 4-stroke outboard, it set a new benchmark for power and performance from a compact and lightweight outboard, and was recognized for this with an NMMA Innovation Award. Utilizing Suzuki’s advanced Lean Burn Control System and Suzuki Precision Control the DF300A delivers remarkable fuel economy over a wide operating range and environmentally responsible operation.  

The new DF300A incorporates “Suzuki Selective Rotation” —the world’s first selective rotation outboard that combines regular and counter-rotation operation into the same outboard. The outboard can be switched to counter-rotation operating by connecting a coupler to a circuit in the engine compartment and changing to a counter rotational propeller.The lower unit is designed with a two-way water pick up inlet, which provides the engine cooling system with increased water flow. 

New Lower Unit 

The biggest changes on the DF300A are found in the outboard’s lower unit, which was redesigned for the Suzuki Selective Rotation system—the world’s first integration of regular and counter-rotation models into a single unit. The system consists of a new drive gear layout in the lower unit that allows the outboard to operate in either regular or counter-rotation mode, and a switch that connects to a circuit in the engine compartment that engages the counter-rotation mode. Like the DF300, the new DF300A utilizes an aggressive final drive ratio of 2.08:1 allowing it to turn 16-inch diameter propeller available in various pitch size for optimum performance on a wide variety of boats. Improvements to gear designs provide greater durability, and adding a two-way water inlet improves water flow into the cooling system for increased cooling efficiency. 

Suzuki Selective Rotation 

In multi-outboard installations on large boats, a counterrotation outboard is usually paired with a regular rotation model to help keep the boat traveling on an even keel and in a straight line. The DF300A is built with special counter rotating gearing in the lower unit, which causes the prop to rotate in the opposite direction. Suzuki Selective Rotation eliminates the need to purchase a dedicated counter-rotation outboard by using a special switch that when connected to a circuit inside of the engine compartment, turns a regular rotation outboard into a counter-rotation model with a counter rotational propeller. This industry first is made possible through a special, unified design of gears, shaft, and bearings in the lower unit that are designed to operate reliably and efficiently in either regular or counter-rotation directions. 

Superior Durability 

With the addition of Suzuki Selective Rotation, gears in the lower unit were redesigned using a different alloy and slightly larger diameters delivering greater rigidity. The gears are specially heat treated creating gears that are highly durable. 

Two-way Water Inlet 

The engine’s cooling system relies on water supplied through low water intakes located on the lower unit. Utilizing this dual low water inlet configuration increases water flow into the lower unit which delivers greater cooling efficiency. Positioning the forward inlet at the gear case nose delivers a greater water supply especially at high speeds. The second inlet is also positioned lower allowing the DF300A to operate in shallow water conditions. 

Newly Designed Low Drag Gear Case 

The DF300A features a redesigned low drag gear case developed to accommodate the new gears utilized in the Suzuki Selective Rotation system. The case itself is actually larger than the previous model to provide increased gear durability, however it is designed with a smoother, more hydrodynamic shape that allows it to move through the water with less drag and greater efficiency. Areas with the highest drag are indicated in red in the illustrations below. The comparison shows that the new design allows the lower unit to slice through the water with less drag. 

Suzuki’s Lean Burn Control System 

Suzuki’s innovative Lean Burn Control System was first introduced on the DF90/80/70 to great acclaim from boaters and the media alike. It predicts fuel needs according to operating conditions allowing the engine to run on a more efficient fuel mixture through the use of a lean air-fuel ratio. It delivers its benefits over a wide operating range, providing significant improvements in fuel economy from low-speed operation into the cruising range. Combining this system with the Suzuki Precision Control, electronic throttle and shift system, allows the operator precise control to increase or decrease the engine RPM for improved fuel economy over a wider range. This combination also delivers smooth power transitions throughout the entire RPM range. In-house testing shows that while cruising, the DF300A is 14% more economical than the original non-Lean Burn DF300 without sacrificing any power of the original DF300. 

O2 Sensor Feedback Control System 

The DF300A is equipped with an O2 Sensor Feedback Control system, which enables emissions to be cleaner and more stable. The system controls the air to fuel ratio across each of the engine’s operating ranges providing an optimum amount of fuel to the engine regardless of rpm. 

Suzuki's Advanced Technology Delivers the Utmost in Performance VVT (Variable Valve Timing) 

Suzuki’s engineers designed the 4.0-liter V6 engine with an aggressive cam profile that delivers maximum output and performance at high rpm. In coupling this cam profile with Suzuki’s advanced Variable Valve Timing (VVT), the DF300A delivers the additional torque that outboards need for accelerating in the low to mid-range. VVT achieves this by adjusting the timing of the intake valves, allowing them to open before the exhaust valves are fully closed, creating a momentary overlap in the timing where both sets of valves are open. Using VVT, this overlap can be increased or decreased by altering intake timing with the camshaft resulting in optimum timing for low and mid-range operation. 

32-Bit ECM and Suzuki’s Multi Point Sequential Electronic Fuel Injection 

Suzuki pioneered the use of multi-point sequential electronic fuel injection in four-stroke outboards with the introduction of the original DF60 and DF70. At the heart of the DF300A’s multi point sequential fuel injection system is the ECM (Engine Control Module), which constantly monitors a large amount of data, in real time, from a series of sensors placed in critical areas on the engine. This comprehensive network of sensors includes the Manifold Absolute Pressure Sensor, Crankshaft Position Sensor, Intake Air Temperature Sensor, Cylinder Wall Temperature Sensor, Camshaft Position Sensor, and Exhaust Jacket Temperature Sensor. Using a very powerful 32-bit computer, the ECM processes data from all of these sensors and instantly calculates the optimum amount of fuel to be injected at high pressure into each of the V6’s cylinders by the multi point sequential fuel injection system. Benefits of this system include reduced exhaust emissions, which allow the DF300A to comply with the California Air Resource Board (CARB) 3-Star emission requirements, lower fuel consumption, smoother starts, crisper acceleration, smoother performance, and maximum efficiency. 

Suzuki Precision Control (Electronic Throttle and Shift Systems) 

Suzuki Precision Control is a technologically advanced computer-based control system that replaces the mechanical control cables found in conventional control systems with electronic wiring that eliminates the source of friction and resistance. While you enjoy smooth, friction free throttle and shift operation, the system’s computer is processing and transmitting commands in real-time to actuators at the engine that deliver precise throttle controls with smoother, decisive shifting. This is most evident in the low rpm range where operation is noticeably smooth and accurate. When combined with Suzuki’s Lean Burn Control System it allows control of fuel and air flow to boost the limit of the controllable revolution range improving fuel economy over a wide operating range. Suzuki Precision Control also features built-in systems that help guard the engine and drive against damage due to mishandling, and its design and simple wiring make installation easy, reducing the time required for rigging and adjustment. The system offers precision control for single, twin or triple installation as well as dual station operation. 

Long Track Intake Manifold 

Another performance enhancing feature on the DF300A is a turned long track intake manifold. Using long intake pipes tuned to provide smooth airflow into the engine the system provides the DF300A with enhanced low end power. 

Large Air Intake with Water Separator

The DF300A is designed with a large air induction port to maximize airflow into the engine in order to obtain maximum power output. The increased airflow produces more low- to mid-range torque and provides a wide power band that is necessary in an outboard engine. Suzuki also designed the system with a water separator, which aids in keeping water out of the electronic throttle body and a heat shield to keep intake air from being heated by the engine. 

Spherical Bore Throttle Body

An 81mm spherical bore throttle body smoothes the turbulent airflow into the engine that occurs as the throttle begins to open. Providing a smoother airflow during acceleration results in increased throttle control and stable engine operation at low rpm. 

Fuel Cooler 

The cooler the fuel the denser it is, and the denser it is the better performance it delivers. Incorporating a fuel cooler in the DF300A’s fuel delivery system cools the fuel before it enters the engine. Providing the engine with an optimum fuel supply results in better combustion and more performance. 

Strengthened Forged Pistons

The upper portion of pistons used in the big V6 engine is treated with an alumite coating that increases heat resistance. A resin coating applied to the piston skirt increases resistance to wear and reduces friction. 

Offset Driveshaft

Suzuki outboards are among the most compact outboards in their respective classes. That’s due in part to the utilization of Suzuki’s proven offset driveshaft system. This design places the crankshaft in front of the driveshaft through the use of intermediate gear reduction. In addition to providing an increase in power performance and adding to the compactness of the outboard, this system moves the outboard’s center of gravity forward, resulting in contribution to weight distribution, balance, directional stability, and less vibration. 

Two-Stage Cam Drive System

The DF300A utilizes a two-stage cam drive system that incorporates both gears and a chain. First stage gears transfer power between the crankshaft and the drive shaft from which a second stage utilizes a chain to deliver power from the driveshaft to the camshaft. This system allows for the use of smaller cam sprockets, which in turn allow for a reduction in valve angles also reducing the size of the cylinder head. An automatic hydraulic tensioner incorporated into the timing chain system keeps the chain properly tensioned and provides years of maintenance-free operation. 

Suzuki Water Detecting System 

Water in the fuel can be the source of poor combustion, lower power output, and corrosion. To protect the engine from moisture in the fuel, the DF300A is the first Suzuki outboard to utilize a water detecting fuel filter that alerts the operator with both visual and audio warnings when water is present in the fuel. 

Water-Cooled Voltage Regulator 

The outboard’s electric system includes a water-cooled voltage regulator that dissipates heat in the regulator to enhance engine durability. 

Fuse Box 

Fuses protecting the DF300A’s electric system are assembled into a single fuse box located under the cowling on the side front-port of the outboard motor, which provides convenient access while offering a clean exterior. 

Highly Reliable Direct Ignition System 

Supplying spark to the big V6 engine is an advanced ignition system that utilizes integral type spark plug caps with built-in ignition coils. The system is controlled by the outboard’s powerful 32-bit computer and provides each cylinder with optimum spark timing. In addition to reducing the number of parts and simplifying the wiring system, this arrangement greatly reduces electronic engine “noise” that can interfere with VHF radios, fish finders, and other marine electronics. 

Easier Maintenance Dual Engine Flush Ports 

The buildup of sand and salt in the engine’s cooling system can lead to engine damage. To aid in reducing such buildup, the DF300A is designed with two freshwater flush ports that make flushing of the cooling system as convenient and easy as possible. With one port located on the rear panel and the second on the front panel, access is easy and flushing out the system is possible whether the boat is in or out of the water. 

Convenient Dual Circuit Charging System 

The DF300A incorporates a dual circuit charging system that can be adapted to accommodate the dual-battery configurations often used on large boats. When used in this configuration the system is designed to charge both the main and auxiliary batteries simultaneously but on independent circuits. With this you can drain down the accessory battery powering your electronics and still have a fully charged main battery for starting the motor. 

Suzuki Trolling Mode System 

Suzuki’s Trolling Mode system provides finer control over engine speed at low rpms to keep your boat moving at a constant speed while trolling. When the system is engaged, revs are controlled with an independent control switch that adjusts engine revs in 50rpm increments over a range spanning from idle to 1,200rpm. The system includes a control switch, which can be mounted nearly anywhere on the console, and a tachometer, and is compatible with Suzuki’s SMIS digital gauges or the dual scale analog gauges. 

Suzuki’s Anti Corrosion Finish 

The outside of the DF300A is covered with Suzuki’s anticorrosion finish that is specially formulated to increase the durability of the engine and help protect parts of the aluminum exterior that are constantly exposed to saltwater. This advanced finish offers maximum bonding to the outboard’s aluminum surface, creating an effective treatment against corrosion.

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