Yanmar TF90 Specifications
| Engine Model: Yanmar TF90 |
| Engine Type: 4-stroke 1-cylinder horizontal water-cooled diesel |
| Total Displacement: 30.1 cu.in (0.49 L) |
| Rated Engine Power: 9 Hp (6.7 kW) at 2200 rpm |
| Fuel System Type: Direct injection |
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The Yanmar TF90 is a horizontal,
single-cylinder, 4-stroke water-cooled diesel engine from the Yanmar TF
series. This engine incorporates a direct injection system combined with
a toroidal piston design, a configuration that generates high torque at
low engine speeds while maintaining low fuel consumption. The TF series
is engineered for stationary and mobile industrial applications where
compact dimensions, reduced vibration, and operational reliability are
required. The horizontal orientation distinguishes this engine from
vertical diesel units, allowing installation in space-constrained
machinery such as power tillers and small water pumps.
The Yanmar TF90 is a single-cylinder, horizontal, 4-stroke, water-cooled
diesel engine featuring direct fuel injection. Displacement is 0.493 L.
The engine block is constructed from cast iron with a horizontally
oriented cylinder. The cylinder head incorporates a direct injection
system with a toroidal piston combustion chamber.
The valvetrain is a pushrod overhead valve design with 2 valves. Cooling
is provided by a liquid-cooled system equipped with a radiator.
Lubrication is a forced-feed system using a trochoid-type oil pump. A
two-shaft balancer system is fitted to reduce vibration inherent to
single-cylinder operation. Starting is manual via a hand-crank
mechanism; an electric start option is available.
Engine Type: Horizontal, 1-cylinder, 4-stroke, water-cooled diesel
Displacement: 0.493 L (493 cc / 30.1 cu.in)
Bore: 85.0 mm (3.35 in)
Stroke: 87.0 mm (3.43 in)
Compression Ratio: 17.9:1 (standard)
Compression Ratio: 16.5:1 (high-altitude variant)
Maximum Power: 6.7 kW (9.0 hp) at 2200 rpm
Rated Power (Continuous): 6.0 kW (8.0 hp) at 2200 rpm
Maximum Torque: 33.7 Nm (24.9 lb-ft) at 1600 rpm
Fuel Injection Timing: 18° BTDC
Fuel Injection Pressure: 19.6 MPa (200 kgf/cm2 / 2840 psi)
Firing Order: Single cylinder (injection every 720° of crankshaft
rotation)
Rotation (viewed from flywheel): Counterclockwise
Aspiration: Naturally aspirated
Combustion System: Direct injection
The cylinder block is manufactured from grey cast iron as a horizontal
monobloc casting. The block is of a single-cylinder design with the
cylinder bore axis oriented horizontally. The parent cylinder bore is
machined directly into the cast iron material without replaceable
liners. The crankcase is integrated into the block casting and houses
the crankshaft main bearings.
A two-shaft balancer system is mounted within the crankcase, driven by
gears from the crankshaft to counteract the primary imbalance inherent
to single-cylinder operation. The block incorporates mounting bosses for
the radiator, fuel tank, and engine frame attachment.
Crankshaft: The crankshaft is forged from carbon steel with a single
throw. A larger crankshaft size than previous series versions improves
strength. The crankshaft is supported by two main bearings. A torsional
vibration damper is fitted to the front end.
Connecting Rod: Forged steel I-beam design with replaceable bearing
shell at the big end. Piston: Cast aluminum alloy with a toroidal
(donut-shaped) combustion bowl in the crown. Three piston rings: two
compression rings and one oil control ring. The toroidal piston design
creates high air swirl, improving fuel-air mixing and enabling the high
torque output at low engine speeds.
The cylinder head is a separate casting manufactured from cast iron. The
head incorporates the direct injection nozzle holder and the combustion
chamber recess that aligns with the toroidal piston crown. The overhead
valve arrangement uses a pushrod actuation system with a camshaft
positioned within the cylinder block.
Two valves are present: one intake valve and one exhaust valve. The
valve train includes rocker arms mounted on a single shaft with
adjustable screw and locknut for valve lash setting.
The fuel system is a direct injection architecture. A Bosch-type inline
injection pump is mounted on the side of the cylinder block and driven
by the camshaft. A mechanical centrifugal governor maintains engine
speed under varying loads. A diaphragm-type fuel feed pump includes a
manual primer lever for system bleeding.
The injection nozzle is a multi-hole type installed in the cylinder
head, spraying fuel directly into the toroidal combustion bowl formed in
the piston crown. Fuel injection pressure is set to 19.6 MPa (2840 psi).
Injection timing is fixed at 18° before top dead center. The fuel tank
capacity ranges from 10.5 L to 11.9 L (2.8 gal to 3.1 gal) depending on
sub-model and equipment configuration.
The lubrication system is a forced-feed, wet-sump design. A
trochoid-type oil pump is mounted on the timing gear case and driven by
the camshaft. The pump draws oil through a suction strainer positioned
in the lower crankcase. Oil passes through a full-flow filter (spin-on
type on later models).
A pressure relief valve maintains system pressure. Total oil capacity is
2.2 L (2.3 qt). An oil level dipstick is located on the side of the
crankcase. The engine is designed for API classification CD or higher
diesel engine oil.
The cooling system is a liquid-cooled circuit equipped with a radiator.
A belt-driven centrifugal water pump circulates coolant through the
cylinder block, cylinder head, and the radiator. A wax-pellet thermostat
regulates coolant flow to maintain the engine within the optimal
operating temperature range.
A cooling fan is mounted on the water pump pulley and shrouded for
efficient airflow through the radiator core. Total cooling water
capacity is 1.65 L (1.7 qt). A hopper tank cooling option is available
for stationary applications where a radiator is not required.
Balancer System: A two-shaft balancer is driven by gears from the
crankshaft. The two shafts rotate at twice crankshaft speed in opposite
directions, generating counter-oscillations that cancel the primary
shaking force of the single-cylinder engine. This system reduces
operator fatigue during extended operation.
Starting System: Manual starting is standard via a hand-crank handle
inserted at the front of the crankshaft. An electric starter motor
option is available for applications requiring key-start convenience.
For electric start variants, the recommended battery is 12 V - 56 Ah
(65D31R specification).
Exhaust System: A large-capacity muffler is fitted to reduce engine
noise during operation.
Air Cleaner: A paper-filter type air cleaner with a cyclone pre-cleaner
is standard equipment.
The TF90’s horizontal orientation results in a low-profile engine
package. The overall length is 672 mm (26.5 in). Width is 331 mm (13.0
in). Height is 496 mm (19.5 in). The dry weight ranges from 86.5 kg (191
lb) to 91 kg (201 lb) depending on the cooling system configuration,
with radiator-cooled versions at the higher end of the range.
Engine Oil Capacity (total): 2.2 L (2.3 qt)
Oil Grade: SAE 10W-30, 15W-40, or 20W-40 meeting API CD, CE, CF, or
higher
Coolant Capacity: 1.65 L (1.7 qt)
Fuel Injection Timing: 18° BTDC (static)
Glow Plug Operation: 5 to 10 seconds pre-heat before starting below 10°C
(50°F)
Oil Change Interval: 200 hours (normal service)
Oil Filter Replacement Interval: 200 hours (at each oil change)
Fuel Filter Replacement: 200 hours
Air Cleaner Cleaning Interval: 50 hours under dusty conditions
Cylinder Head Bolts: 50 to 60 Nm (37 to 44 lb-ft).
Main Bearing Cap Bolts: 70 to 80 Nm (52 to 59 lb-ft).
Connecting Rod Bolts: 40 to 45 Nm (30 to 33 lb-ft).
Rocker Arm Shaft Bracket Bolts: 20 to 25 Nm (15 to 18 lb-ft).
Rocker Arm Adjustment Locknuts: 10 to 15 Nm (7 to 11 lb-ft).
Flywheel Bolts: 60 to 70 Nm (44 to 52 lb-ft).
Crankshaft Pulley Bolt: 100 to 120 Nm (74 to 89 lb-ft).
Intake and Exhaust Manifold Nuts: 15 to 20 Nm (11 to 15 lb-ft).
Injection Pump Mounting Nuts: 20 to 25 Nm (15 to 18 lb-ft).
Injector Holder: 40 to 50 Nm (30 to 37 lb-ft).
Oil Pan Bolts: 10 to 15 Nm (7 to 11 lb-ft).
Glow Plug: 10 to 15 Nm (7 to 11 lb-ft).
The Yanmar TF90 engine was deployed across a range of small
agricultural, industrial, and marine applications.
Power Tillers (Hand Tractors): The TF90 was widely used as a power
source for two-wheel walking tractors and hand tillers in rice-growing
regions. The horizontal orientation provided a low center of gravity,
and the balancer system reduced handle vibration. Manufacturers included
Yanmar, Kubota, and various local assemblers in Southeast Asia.
Water Pumps: The engine powered centrifugal irrigation and drainage
pumps for agricultural fields, flood control, and construction site
dewatering. Direct-coupled or belt-driven configurations were offered.
Rice Hullers and Small Mills: The TF90 was installed in stationary
agricultural processing equipment, including rice hullers (huskers),
rice polishers, corn grinders, and peanut shellers. The engine’s low
fuel consumption was advantageous for off-grid operations.
Small Marine Propulsion: The engine was used as an inboard power source
for small fishing boats and utility craft in coastal and inland waterway
regions. A marine gearbox with reverse capability and a water-cooled
exhaust elbow were added for these applications.
Electric Generators: The TF90 powered small portable generator sets
rated at 5.0 kW to 7.0 kW for rural electrification, construction sites,
and emergency backup. The continuous rating of 6.3 kW matched typical
generator head sizes.
Compressors and Industrial Equipment: The engine was installed as a
prime mover for small air compressors, concrete mixers, winches, and
other construction equipment where diesel durability was preferred over
gasoline engines. The TF90 remained in production through the 2000s,
with later electronic common-rail single-cylinder engines gradually
replacing it in high-volume applications.
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| Industrial Engines Technical Specifications |
| Car Engines Technical Specifications |
| Small Engines Technical Specifications |
| Outboard Engines Technical Specifications |
