New Honda portable BF4, BF5 and BF6: Engine Review

Honda Marine has launched a new range of small portable four-stroke outboard engines. With speedy, one-pull manual starting, vibration-absorbing engine mounts, and a 43 minute run-time on the built-in fuel tank, the new single cylinder 4, 5 and 6hp triplets are ideal for auxiliary applications and for powering tenders and small fishing craft.

OVERVIEW
- Honda BF4 and BF6 available for testing
Marine journalists from around the country assembled on the Gold Coast last week for the official Australian launch of Honda’s brand new BF4, BF5 and BF6 small portable four-stroke outboard engines.

The new Honda portables, identical but for their power outputs (regulated by airflow and rpm), replace the outgoing Honda BF5 which has been an important model in the Honda Marine range for more than two decades.

Surprisingly, perhaps, the new Honda mini portables are no lighter than the older model, coming in at 27kg in 308mm short shaft (15in) configuration. However, the BF4, BF5 and BF6 incorporate a range of new technologies and design features to make them much more user-friendly, economical and reliable.

During the local launch last week, two of the three new Honda portables were on display and available for a brief test and review. The entry 4hp model was fitted to a small Sirocco inflatable tender, while its 6hp big brother was clamped to the transom of a Blaze aluminium dinghy. We spent most of our time with the smaller motor and it proved very easy to use.

DESIGN SPECS
- Proven design with new technologies
The new Honda BF4, 5, 6 share a single-cylinder, overhead-valve engine configuration with a displacement of 127cc and a bore x stroke of 60mm x 45mm.

The Hondas have a gear ratio of 2.08:1 and are available with five different sized propellers to suit different applications. The standard propeller is a three-blade 7 7/8in x 7 1/2 pitch.

The portable Hondas have a standard forward-neutral-reverse gear shift with a twist-grip throttle and the gear shift lever located in the traditional position on the side of the engine — instead of at the front as with some other brands.

The outboards are available in 308mm short shaft (15in) and 508mm long shaft (20in) configuration with the lightest models weighing 27kg — some 3kg more than the lightest engine in this class.

The portable Hondas are nevertheless easy to carry and to transport, thanks to re-designed, well-placed carry handles and a tiller-arm that can be folded down and out of your way.

There is no electric start option for the new Hondas but they are very easy to pull start by hand. A new automatic decompression system opens up the exhaust valve during the starting process so there is little compression resistance when you tug on the starter cord. Starts are subsequently quick and easy when the engine is hot or cold.

In line with competitor engines in this size class, the new Honda 4, 5 and 6hp now have an internal fuel tank. It has a capacity of 1.5 litres and Honda claims this is enough to run the 6hp model at wide open throttle for 43 minutes.

As you would expect the Hondas are also configured so that you can run them off a separate, remote 12L fuel tank, which is available as an option.

PRICE AND EQUIPMENT
- Stocks rolling out now from your Honda dealer
Honda has advised that stocks of the new BF4, BF5 and BF6 will be rolled out from the end of October 2016 – so expect to see them at your local Honda dealer soon.

The new portables will be priced from $2399 for the BF4, $2449 for the BF5 and $2499 for the BF6. Set aside a further $117.65 for a 12L Honda portable fuel tank (available BF5 and BF6 only).

These recommended retail prices are higher than most competitor brand four-stroke models, but we would expect real world dealer prices to be a bit sharper.

With regard to features and equipment, the new Hondas have everything you would expect from a modern four-stroke portable outboard engine, including shallow water drive, start-in-gear protection, rpm limiter, multiple trim positions (manually operated with trim-pin slots), kill switch with safety lanyard, and warning systems for potential engine problems.

Of particular note is the ECU operated oil pressure monitoring system that cuts engine rpm to a 'limp home' 2300rpm in the event of a drop in oil pressure or other potentially engine damaging condition.

On the front of the engine there is also a very bright oil pressure warning light. It glows green when all is good, but turns to red when there is a problem.

As the new Honda portables are not available with electric start, you can have an optional 6 amp 12 volt charging system fitted so you can power a battery to run electronics, navigation lights, etc. Dealer pricing for the charging system has yet to be determined.

A new convenience feature for the Honda 4, 5, and 6hp portables is the one-touch stop switch, which is claimed to be unique in class. Turning the engine off with most other portable engines on the market requires you to hold down the stop button until the motor shuts down completely... otherwise it will often chug back into life again.

DRIVE IMPRESSIONS
- Smooth, progressive power delivery with low tiller and engine vibration
During the launch of the new Honda four-strokes, attending journalists were given two boats to play with: a BF6 powered alloy dinghy, and a BF4 powered inflatable. We spent most time with the latter combination.

Initial impressions were positive. The little Honda is a neat looking unit with a compact powerhead and a sleek one-piece cowling that is easy to remove single-handed, as there is just the single clip/fastening at the back of the engine.

Removing the cowling reveals the integral fuel tank, single carburetor on the right hand side and an easily viewable and drainable fuel filter beneath that. The oil reservoir is accessed from the opposite side.

The engine controls are well positioned and well designed. The tiller-arm was just the right length and the twist-grip throttle felt comfortable in the hand.

Some people might prefer the front-mount gear shift of some portable outboards but we had no issues with the side mounted lever on the new Hondas. The shift operation was good too — firm and direct with a reasonable throw length so you can easily tell which gear you are in.

Lifting the engine up or down, and engaging shallow water drive is simple and intuitive. Swapping trim pins can also be completed in just a few moments.

Thanks to Honda’s new automotive decompression system the new engines can be started quickly and with very little effort. Providing you set the throttle to "start" (which increases the rpm) then they will kick into life after one short tug on the starter cord.

When cold you may need to dial in some choke, but the engines still start promptly.

Moving away from the beach in the test rig we noted the steering was smooth, well-weighted, and with enough steering lock for close quarter maneuvering.

One of the key selling points for the new portable Hondas is the introduction of new rubber engine mounts to help isolate and or absorb the engine vibration that is an inherent issue with single-cylinder engines.

There was very little vibration felt through the tiller while at rest or when running at wide open throttle.

With regard to power and performance it is difficult to accurately rate the new Hondas without direct (side by side) comparison to other brands, but the little BF4 and BF6 that we tested felt quite strong with a smooth and linear power delivery.

VERDICT
-  Terrific new four-stroke portables for tenders and small fishing craft
Honda’s new BF4, BF5 and BF6 engines are welcome additions to the small portable four-stroke engine class. These clean-running, fuel sipping little four-strokes are user-friendly and deliver smooth, low-vibration performance.

These sweet little engines are perfect for auxiliary engine applications, and for powering tenders, fishing canoes, kayaks, inflatables and car-topper tinnies.

For a limited time, the new Honda portables also come with an industry leading seven-year recreational warranty and three-year commercial warranty. Check with your Honda dealer for full details.

Specifications: Honda BF4, BF5, BF6
Pricing: BF4 $2,399, BF5 $2,449, BF6 $2,499
Engine type: four-stroke, overhead valve
Cylinders: Single cylinder
Fuel Delivery: Carburetor
Weight: From 27kg
Displacement: 127cc
Bore x Stroke: 60mm x 45mm
Max.output: 4hp @ 5000rpm, 5hp @ 5,500rpm, 6hp @ 6,000rpm
Shaft length: S:381mm (15”), L:508mm (20”)
Alternator/charging: Optional 6 amp (12 volt)
Trim method: Manual trim & tilt
Gear ratio: 208:1
Gear shift: F-N-R
Servicing: Six monthly (or every 100 hours after first 10 hour service)
Fuel capacity: 1.5L internal tank
Warranty: Seven years (recreational use)

Supplied by:
Honda Marine
Locate a dealer at marine.honda.com.au.