Honda BF75 and BF90: Lightweight Powerhouses

Honda BF90HP powering a RIB

Honda Marine’s BF75 and BF90 afford boaters the fuel efficiency and quiet operation of Honda’s legendary technology combined with the lightweight and explosive acceleration traditionally associated with two-stroke outboards. The pair’s 1.5-litre, in-line 4-cylinder engine boasts Honda’s exclusive Boosted Low Speed Torque (BLAST) system, Variable Valve Timing and Electronic Lift Control (VTEC™ – BF90), Lean Burn Control, and Three Way Cooling.
BLAST Off
Ideal for smaller speedboats, centre consoles, inflatables, pontoons and skiffs, Honda’s BF75 and BF90 EFI redefine four-stroke performance with the patented BLAST system.
Holeshot and acceleration are dramatically improved by advancing ignition spark timing to within one degree of the knock limit during “hammer down” acceleration. The Engine Control Module (ECM) then steps in to increase injector timing, creating a more potent air/fuel mixture. The resulting boost in available torque at low rpm contributes to a strong holeshot to get the boat up on plane quickly. The ignition spark timing is appropriately adjusted under slower throttle advancement, ensuring a leaner air/fuel mix and class-leading fuel efficiency.
Further contributing to the engines’ outstanding fuel efficiency is Honda’s exclusive Lean Burn Control, which pairs the ECU with an oxygen (O2) sensor to adjust the air/fuel mixture according to speed and load, maximizing efficiency in “cruise mode.”
Derived from racing and first appearing on the Acura NSX sports car, VTEC™ (BF90) utilizes mild cam lobes to operate the intake valves at low rpm, and then engages a high-output lobe for high-rpm operation. The resulting boost in available power provides outstanding mid-range acceleration.
Further contributing to the pair’s explosive performance is Honda’s high-performance gear case. A longer anti-ventilation plate helps trap water flowing to the propeller to minimize porpoising, while a streamlined front and longer bullet reduce drag for enhanced acceleration and fuel efficiency. A front splash plate reduces spray from the hull bottom, maintaining a dry deck above, and a 2.33:1 gear ratio affords the use of 13- to 14-inch diameter propellers for heavier loads.

Honda BF75HP

The engines’ best-in-class 44-amp alternator (35 amps of battery charging), ignition, and other critical electrical components are mounted near the top of the powerhead to ensure that all are kept cool and dry.
High Performance in a Durable Package
To ensure long term durability, Honda engineers designed the first individually-controlled cylinder cooling system for outboard engines – Three Way Cooling. The system reduces engine heat by allowing the cylinder head to run slightly cooler than the cylinder block, greatly reducing engine wear.
A Single Overhead Camshaft (SOHC) design uses dual intake valves to deliver the optimal air/fuel mixture for maximum torque and combustion efficiency. In addition, a Multi-Port, Programmed Electronic Fuel Injection system (PGM-FI) accurately controls ignition timing during start-up to provide instant throttle response and outstanding fuel efficiency.
Top-mounted electronics are a standard feature on both engines. The alternator, ignition, and other critical components are mounted near the top of the powerhead to ensure that all are kept cool and dry. By extension, a camshaft-driven, automotive-style oil pump promotes long-term durability of critical engine components.

Honda BF75/90 Cover Off

The BF75 and BF90 boast an Engine Alert System that uses audio and visual cues, as well as rpm reduction circuits to alert the operator of conditions which can contribute to engine damage, such as overheating, low oil pressure, and over-revving. A freshwater flushport functions to flush debris and salt water out of the engine, while Honda’s patented 4-Front Corrosion Protection System features a double-sealed, multi-layered paint process – both features extend the life of the outboards in harsh marine environments.
The BF90 is available in both 20- and 25-inch shaft models, while the BF75 is offered in a 20-inch shaft length. All new Honda outboard engines sold for recreational use offer an industry-best True 3-year, non-declining limited factory warranty that is the same on the last day as it is on the first.
Technical Specifications: Honda Marine BF75

ENGINE
TYPE	Four-Stroke In-line 4-Cylinder
DISPLACEMENT	1,496cc (91.3 cubic in)
BORE & STROKE	73 x 89.4 mm (2.87 x 3.52)
FULL THROTTLE HP RANGE	4,500 – 5,500 RPM
HP RATING AT PROPSHAFT	75HP @ 5,500RPM
VALVE TRAIN	SOHC
VALVES PER CYLINDER	4
FUEL DELIVERY	Programmed Electronic Fuel Injection (PGM-FI)
IGNITION SYSTEM	Microcomputer Controlled
STARTING SYSTEM	Electric
LUBRICATION	Wet Sump
COOLING SYSTEM	Water Cooled
ALTERNATOR	44 Amp (546 watts)
BATTERY CHARGING POWER	35 Amp (433 watts)
TRIM RANGE	-4° to +16°
TILT RANGE	68°
DRIVE
GEAR RATIO	2.33:1
GEAR SHIFT	F-N-R
PROPELLER	Optional
DIMENSIONS
TRANSOM HEIGHT(S)	(L) 508 mm
DRY WEIGHT (TILLER)	(L) 171 kg
DRY WEIGHT (REMOTE)	(L) 165 kg

Technical Specifications: Honda Marine BF90

ENGINE
TYPE	Four-Stroke In-line 4-Cylinder
DISPLACEMENT	1,496cc (91.3 cubic in)
BORE & STROKE	73 x 89.4 mm (2.87 x 3.52)
FULL THROTTLE HP RANGE	5,300 – 6,300 RPM
HP RATING AT PROPSHAFT	90HP @ 5,500RPM
VALVE TRAIN	SOHC
VALVES PER CYLINDER	4
FUEL DELIVERY	Programmed Electronic Fuel Injection (PGM-FI)
IGNITION SYSTEM	Microcomputer Controlled
STARTING SYSTEM	Electric
LUBRICATION	Wet Sump
COOLING SYSTEM	Water Cooled
ALTERNATOR	44 Amp (546 watts)
BATTERY CHARGING POWER	35 Amp (433 watts)
TRIM RANGE	-4° to +16°
TILT RANGE	68°
DRIVE
GEAR RATIO	2.33:1
GEAR SHIFT	F-N-R
PROPELLER	Optional
DIMENSIONS
TRANSOM HEIGHT(S)	(L) 508 mm
	(X) 635 mm
DRY WEIGHT	(L) 166 kg
	(X) 172 kg