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Johnson Tracker 40 Specifications
| Engine Model: Johnson Tracker 40 Hp |
| Engine Type: 2-stroke 2-cylinder gasoline outboard engine |
| Total Displacement: 49.7 cu.in (0.81 L) |
| Rated Engine Power: 40 Hp (29.4 kW) at 5500 rpm |
| Fuel System: Downdraft carburetor |
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| General Technical Data |
The Johnson Tracker 40 Hp is a two-cylinder,
two-stroke outboard engine designed and marketed as a value-oriented
powerplant, often associated with boat package deals. This engine
provides a balance of adequate power, mechanical simplicity, and
competitive weight for a range of small to medium-sized fishing and
recreational boats. As a carbureted two-stroke with oil injection, it
offers the convenience of automatic lubrication while maintaining a
straightforward, serviceable design.
The Tracker 40 delivers its rated Hp with a focus on reliable operation
and ease of use rather than peak performance. It is recognized for its
role as an accessible and functional motor for entry-level boaters and
anglers, providing dependable propulsion for aluminum fishing boats and
similar craft on inland waters and protected bays.
Engine Designation: Johnson Tracker 40 Hp
Engine Type: Two-stroke, loop-charged scavenging
Cylinder Arrangement: Inline 2-cylinder
Bore: 2.8 inches (71.0 mm)
Stroke: 2.7 inches (68.6 mm)
Displacement: 49.7 cubic inches (0.815 liters)
Compression Ratio: 6.0:1
Rated Power: 40 Hp at (29.4 kW) 5,500 RPM
Full Throttle Operating Range: 5,200 to 5,800 RPM
Ignition System: Electronic Capacitor Discharge Ignition (CDI) with
electronic timing advance, managed by a solid-state power pack.
Starting System: 12-volt electric starter motor with solenoid
(standard).
Charging System: 16-amp alternator with solid-state voltage regulator.
Direction of Rotation: Standard right-hand rotation (clockwise when
viewed from above).
Gear Ratio: 2.27:1
Gear Shift: Manual shift via cable actuation (remote models) or
integrated tiller handle.
Exhaust System: Through-the-propeller-hub underwater exhaust.
Fuel Requirement: 87 octane (R+M)/2 unleaded gasoline. Oil is supplied
via a separate injection system.
| Cylinder Block |
The cylinder block is a single aluminum alloy casting containing both cylinder bores in an inline configuration. This monoblock design ensures structural rigidity and simplifies assembly. The block incorporates cylinder bores that are finished with a durable coating or fitted with iron liners, depending on the specific production year.
A one-piece forged steel crankshaft rotates within the block, supported by three main bearings. The block casting includes internal transfer passages that route the incoming air-fuel-oil mixture from the crankcase to the cylinders. External mounting points are provided for the intake manifold, oil pump, and ancillary components. The design prioritizes manufacturing efficiency and serviceability.
| Cylinder Head and Valves |
This two-stroke engine operates without poppet valves. Gas exchange is managed entirely by piston-port timing. A single aluminum alloy cylinder head assembly seals both cylinders to the block. The combustion chamber is a machined cavity designed to promote effective loop scavenging, where the incoming charge is directed in a loop pattern to expel exhaust gases.
The head shape works in conjunction with the piston crown to optimize this process for efficient cylinder filling. The cylinder head is sealed with a gasket and secured by multiple through-bolts. Spark plugs are threaded directly into the cylinder head.
| Fuel System |
The fuel system is a carbureted design. It consists of a single fixed-jet downdraft carburetor that feeds both cylinders via a divided intake manifold. A diaphragm-type fuel pump, operated by crankcase pressure pulses, draws pure gasoline from the fuel tank and delivers it to the carburetor.
The carburetor is calibrated for a specific air-fuel ratio and generally lacks user-adjustable mixture screws. The defining feature is that the fuel delivered to the carburetor is gasoline only; oil is introduced separately by the oil injection system. A fuel filter is located in the line or within the fuel pump assembly.
| Lubrication System |
The lubrication system is an automatic oil injection system, often the VRO (Variable Ratio Oiling) or a simpler demand-type system. It consists of a dedicated remote oil tank, an oil pickup, and a mechanical oil pump mounted on the engine. The pump meters outboard motor oil directly into the engine's intake manifold or carburetor throat.
The oil delivery rate is modulated by engine vacuum and RPM, varying the effective oil-to-gas ratio from approximately 150:1 at idle to 50:1 at wide-open throttle. The system includes a warning horn to alert the operator to low oil level or pump failure. Using NMMA TC-W3 certified outboard oil is mandatory.
| Cooling System |
The cooling system is a standard raw water cooling system. A rubber impeller water pump, located in the gearcase, draws ambient water through the intake screens. Coolant water is circulated under pressure through passages in the cylinder block and cylinder head.
A thermostat regulates engine temperature, maintaining a consistent operating range. A visual tell-tale stream provides continuous confirmation of adequate water pump operation. The system is designed for reliable heat dissipation under normal operating conditions.
| Other Systems |
Electrical System: 12-volt negative ground. The system includes the
alternator, a voltage regulator, a CDI power pack, a starter solenoid,
and a warning horn module for the oil injection system. Power Trim and
Tilt: A hydraulic trim and tilt system is standard on most Tracker 40
models. It is operated by a 12-volt electric motor driving a hydraulic
pump. Exhaust System: Tuned exhaust passages within the mid-section.
Exhaust gases are water-cooled and silenced before being expelled
underwater through the propeller hub. Gearcase (Lower Unit): A durable
aluminum alloy gearcase houses the driveshaft, propeller shaft,
forward/neutral/reverse gears, and the water pump. It is filled with
manufacturer-recommended gearcase lubricant. Controls: Utilizes standard
mechanical push-pull cable controls for throttle and shift functions on
remote models.
| Dimensions and Weight |
Dry Weight (Approximate): 200 to 215 lbs (91 to 98 kg) for a standard 20-inch shaft electric start model with power trim and tilt. Weight can vary based on specific model year and exact features. Shaft Length: 20 inches (508 mm) is the standard and most common offering. Overall Dimensions: The inline two-cylinder configuration results in a narrow and compact powerhead, contributing to a favorable power-to-weight ratio and straightforward installation on various transoms.
| Maintenance Data |
Spark Plugs: Champion QL77JC4 or equivalent. Gap setting: 0.040 inches
(1.0 mm). Replace every 100 operating hours or annually.
Fuel Filter: An inline water-separating fuel filter is installed. This
filter requires regular inspection, water draining, and element
replacement as specified.
Water Pump Impeller: Replace the water pump impeller every two years or
300 operating hours, whichever occurs first.
Gearcase Lubricant: Drain and refill the gearcase lubricant annually or
every 100 operating hours. Inspect the lubricant for water contamination
(milky appearance).
Oil Injection System: Verify oil pump operation and hose integrity
annually. Ensure the remote oil tank is filled with correct oil. The
system must be primed after any service that introduces air into the oil
line.
Link and Sync: The procedure to synchronize the carburetor throttle
opening with the ignition timing advance is recommended during tune-ups
or if rough running is observed.
Anode Inspection: Inspect and replace the sacrificial zinc anode on the
lower unit as needed to protect against galvanic corrosion.
| Tightening Torques |
Cylinder Head Nuts/Bolts: 18-20 lb-ft (24-27 Nm). Tighten in a
crisscross pattern in progressive steps.
Spark Plugs: 15 lb-ft (20 Nm).
Flywheel Nut: 45-50 lb-ft (61-68 Nm). Requires a crankshaft locking tool
or piston stop for proper installation. Main Bearing Cap Bolts: 18-20
lb-ft (24-27 Nm).
Connecting Rod Cap Nuts: 12-14 lb-ft (16-19 Nm). Use new cotter pins
upon reassembly.
Gearcase Drain/Fill Screws: 40-50 lb-in (4.5-5.6 Nm).
Propeller Nut: 45 lb-ft (61 Nm). Secure with a new cotter pin.
Engine Mount (Clamp Bracket) Bolts: 40 lb-ft (54 Nm).
Carburetor Mounting Nuts: 40-50 lb-in (4.5-5.6 Nm).
| Boat Applications |
The Johnson Tracker 40 HP is engineered as a practical and economical
power source for a specific segment of recreational boating. Primary
Power: The intended application is as a single engine on smaller fishing
and utility boats from 13 feet to 18 feet in length. Boat Types:
Aluminum deep-V and modified-V fishing boats, jon boats, small
fiberglass skiffs and center consoles, and light pontoon boats.
Common Hull Brands: This engine was frequently sold as part of packaged
boat, motor, and trailer combinations. It is closely associated with the
Tracker brand of boats sold by Bass Pro Shops, and was also commonly
installed on hulls from manufacturers such as Lowe, Alumacraft, G3, and
Crestliner during its production period in the 1990s and early 2000s.
Its role was to provide reliable, manageable power for entry-level and
value-conscious boaters, making it a common sight on lakes and rivers
across North America.
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