Honda ST1300 has a Liquid-cooled DOHC (Dual Overhead Cam), 4 valves per cylinder, four-stroke, longitudinally-mounted 90° V-four cylinder 1261cc engine.
engine. This longitudinally mounted powerplant provides the perfect blend of power, smoothness, efficiency, and reliability that discerning long-distance riders demand.
Honda ST1300 Engine Displacement & Configuration
The Honda ST1300 engine displacement is 1261cc oversquare 78mm bore and 66mm stroke.
This oversquare configuration favors high-rpm power delivery while the V4 architecture results in inherent smoothness.
Honda ST1300 Engine Configuration
The cylinders in Honda ST1300 are arranged in a compact 90° V angle. This unique engine configuration allows the engine to be mounted longitudinally in the chassis.
Bore & Stroke
The 78mm bore and 66mm stroke serve to boost power output while maintaining excellent throttle response.
The relatively large bore diameter allows for larger intake and exhaust valves that promote airflow.
The shorter stroke length enables the ST1300 engine to rev more freely to its 9000 rpm redline.
Together, the oversquare bore and stroke make for a free-revving yet torquey powerplant.
Compression Ratio
To optimize efficiency, Honda engineers utilized a relatively high 10.8:1 compression ratio in the ST1300 engine.
The higher the ratio, the more the fuel/air mixture is compressed before ignition, leading to more complete combustion.
The 10.8:1 Compression Ratio balances efficiency and reliability.
| Engine Capacity/Engine Displacement | 1261cc |
|---|---|
| Engine Oil Capacity | 4.2 quarts |
| Engine Configuration | longitudinally- mounted 90° V-four cylinder |
| Engine Type | V4, four-stroke |
| Fuel System | PGM-FI with automatic enricher circuit, four-36mm throttle bodies, 12 holes per injector |
| Bore x Stroke | 78.0 x 66.0 mm (3.1 x 2.6 inches) |
| Compression Ratio | 10.9:1 |
| Camshaft Valvetrain Configuration | Double Overhead Cams/Twin Cam (DOHC) |
| Maximum power Output | 126 hp |
| Maximum Torque | 125.00 Nm @ 6,000 RPM |
| Cooling system | Liquid |
| Transmission type | Shaft Final Drive |
Valvetrain Configuration
The V4 engine utilizes a DOHC (dual overhead cam) valvetrain with four valves per cylinder.
This provides maximum breathing at high rpm along with an optimized combustion chamber shape.
The cams actuate the valves directly via shim-adjusted bucket tappets, enabling an extended 16,000-mile service interval.
Honda ST1300 Fuel Injection System
Advanced PGM-FI electronic fuel injection delivers the ideal air/fuel mixture under all conditions.
The system uses four 36mm throttle bodies, each housing 12-hole multi-point injectors. Fuel is delivered at 50psi for optimal atomization.
Fuel injection is managed by a 3D digital ECU for smooth throttle response.
Liquid Cooling System
Keeping temperatures under control is a large-capacity liquid cooling system.
Coolant jackets surround the cylinder and head while a high-output 740w alternator aids heat dissipation by being centrally located between the cylinder banks.
Maintaining proper operating temperatures enhances power delivery and engine longevity.
Horsepower and Torque
The Honda ST1300 engine produces a maximum horsepower of 126 hp at 8,000 rpm. The peak torque output is 85 ft-lbs at 6,500 rpm.
ST1300’s broad torque curve offers strong acceleration from as low as 3,000 rpm, building smoothly towards the 8,000 rpm redline.
While stock power is strong, the ST1300 engine is highly tuneable for even more horses.
Popular mods include free-flowing air intake kits, high-flow exhaust systems, fuel controllers, and engine management chips.
These bolt-on upgrades typically add a horsepower of 5-10hp throughout the rev range.
Performance Metrics
The Honda ST1300 engine is capable of achieving a top speed of 140+ mph (225 km/h).
Such figures are impressive for a sport-touring motorcycle.
ST1300 can go from 0-60 mph in 3.84 sec. The quarter-mile acceleration time of the ST1300 is 12.5 sec.
Transmission
The Honda ST1300 has a cassette-type five-speed transmission and a 45-mm HMAS cartridge fork in the front.
Dampers on the transmission main shaft, clutch, and driveshaft reduce noise, vibration, and drive line lash.
Honda ST1300 has a multi-plate wet clutch that’s hydraulically operated.
The transmission is generally reliable if properly maintained. ST1300’s transmission problems include difficult shifts, gear slippage, and bearing wear at high mileage.
Honda ST1300 Engine Oil
Honda ST1300 has an engine oil capacity of 4.2 quarts. It uses a trochoid-type oil pump to maintain good pressure across the operating range.
Full-flow filtration through an engine oil filter. The main oil gallery feeds crankshaft journals and connecting rod bearings
Additional galleries route engine oil to camshaft journals, valve train, and cylinder head.
Relieves oil pressure for clutch pack lubrication. Utilizes oil jets aimed at the undersides of pistons.
An oil cooler helps maintain proper oil temperature during high loads. The engine oil filter is easy to access.
ST1300 Fuel Efficiency
Fuel Efficiency ranges from 40-50 mpg based on the riding style and the type of road.
Ride between 55-70 mph for the best fuel efficiency.
Use gasoline with a pump octane number of 91 or higher for best mpg numbers.
Emission Standards
Honda ST1300 complies with EPA, CARB, and Environment Canada exhaust emissions regulations.
Honda ST1300 also complies with EPA noise emission standards, staying under 80 dB at 50 feet at highway speeds.
The catalytic converter used in the muffler helps reduce hydrocarbon, carbon monoxide, and nitrogen oxide emissions.
Hassle-Free Maintenance
While powerful, the liquid-cooled V4 is designed for infrequent maintenance.
Adjusting the shim-under-bucket valves takes just minutes at intervals of 16,000 miles. We have an article on ST1300 valve adjustments to know more about valve clearance.
Electronic fuel injection eliminates carburetor synchronization.
The ST1300 engine is also extremely accessible thanks to its longitudinal layout, making DIY servicing a breeze.
Cutting-Edge Technology
Several innovative features enable the Honda ST1300 engine to deliver ample smooth power while meeting modern emissions standards.
These include the Programmed Fuel Injection system that precisely meters fuel, a closed-loop oxygen sensor providing real-time feedback for the EFI system, and two catalytic converters scrubbing the exhaust.
By incorporating composite cylinder sleeves, Honda significantly reduced friction compared to an iron liner.
This allows higher rpm operation with less power loss.
The starter system uses lightweight gears to reduce mechanical drag. Even the alternator placement between the cylinder banks improves airflow for better cooling.
ST1300 Engine Reliability
With its high-tech features and over-engineered components, the ST1300 engine consistently demonstrates the excellent dependability Honda is known for.
The strong internals regularly achieve over 100,000 trouble-free miles.
And this level of reliability comes without sacrificing performance – the ST1300 produces 126hp at just 8000 rpm.
We have an article on the reliability of the ST1300.
The Competitive Edge
The ST1300 stands out against rivals thanks to its powerful yet compact 90° V4 configuration.
Many competitors use larger Inline-Four engines that struggle to match the Honda’s silky smooth power delivery.
And few can compete with the ST1300’s combination of efficiency, longevity, and everyday usability.
After all, this high-tech V4 was designed for the long haul.
In summary, the ST1300 engine is purpose-built for the rigors of long-distance sport touring.
Its carefully designed architecture bore and stroke dimensions, advanced fuel injection, and liquid cooling come together to deliver a powerplant that provides endless smooth power and signature Honda reliability.