Honda BF135 outboard engine review

Originally published in TrailerBoat #291 January / February 2013.

HONDA BF135 OUTBOARD

The Honda BF135 outboard engine develops 133.1hp at 5500rpm with a WOT rev range of 5000-6000rpm. The 2354cc in-line four-cylinder engine has DOHC actuation for the 16 valves, which are driven by chain. This is important because it's an interference engine.

The only belt drive is for the 40A voltage-regulated alternator, which produces 30A at 1000rpm. Twin counter-rotating balance shafts virtually eliminate harmonic vibration and the gear ratio is a usefully low 2.14:1. The extra-longshaft (25in) model has a dry weight of 221kg.

The dual-stage induction is a carry-over from when the engine was first released almost a decade ago. This system lengthens the air intake flow to increase low-rpm torque, then switches to a shorter passage at 4000rpm to improve top-end power.

Blast and ECOmo are more recent addition on the Honda BF135 outboard motor. Boosted low-speed torque advances the ignition timing and, combined with the richer air / fuel ratio (12:1), increases bottom-end torque for less holeshot lag. Once the hull is planing, the air / fuel ratio leans out to 18:1 on ECOmo mode, going back to 14.7:1 as the engine approaches WOT.

The Honda BF135 outboard motor has a three-star OEDA exhaust emissions rating and a recreational-usage warranty of five years.

Rather sensibly, the valve clearance is easily checked using a feeler gauge and 10mm spanner every 200 hours, which is significantly simpler and cheaper than having to set the clearance using shims after withdrawing the camshafts. Honda recommends servicing the BF135 every 100 hours, or annually after the first 20, and Honda's own FCW (Four Cycle Watercooled) SAE 10W30 oil will provide adequate protection for climates of all temperature ranges.

Given an oxygen sensor is fitted to the exhaust system, the BF135 will provide more torque and power when using premium unleaded (95 RON) than on standard non-E10 unleaded. The better engine efficiency means you get something back for the higher fuel cost.

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ON THE WATER

The poor four-stroke 115hp outboard that the review Honda BF135 hp outboard replaced on the Quintrex 600 Freedom Sport bowrider had been subjected to a very hard life, and was due for its own (long) summer holiday.

Swinging a 17in-pitch stainless steel Solas prop and pushing a total of 1500kg, including three adults, the demo BF135 appeared to be slightly over-propped on this hull. But according to Cove Marine, which supplied the demo engine, this setup seems to provide the best blend of performance and fuel efficiency.

The demo engine started instantly whether it was hot or cold, with no oil smoke appearing at any time and very low vibration levels through the hull. Providing the anti-ventilation plate was kept at least three-quarters immersed, power astern was good and the gearshift was progressive - not clunky like some others in this power range. The variable trolling rev adjustment from 650-900rpm in increments of 50rpm is a nice touch.

Holeshot performance was strong, although obviously not as quick as a comparable-output DFI two-stroke. But is this important if you choose a de-stressed engine? No prop ventilation occurred through tight turns at 4000rpm, and the Honda BF135 outboard motor was so quiet at or near WOT we could talk normally at the helm. That's what a stress-free environment is all about.

THE TRADE-A-BOAT VERDICT

Cove Marine sure fitted the Honda BF135 engine to the right hull. The Freedom Sport range is all about family fun, so what better than a lazy and non-intruding engine to fit that image. Honda Marine has done a great job of upgrading this engine with all the fuel-saving goodies Japanese manufacturers excel at, without needing to fit variable intake valve timing or other complexities.

As the world increases in complexity, it's good to take a step back and enjoy what boating should be about: fun and family aboard a big roomy bowrider, effortlessly powered by a friendly engine.

HONDA BF135 PRICE

As of December 2012, the extra-longshaft Honda BF135 outboard motor had a price of $19,199 RRP with a spare Solas prop for $650.

Thanks to Cove Marine - 60 Frederick Drive, Oyster Cove, NSW, 2318, (02) 4982 4832 or covemarine.com.au - who supplied the demo Honda BF135 for this test.

HONDA BF135 PERFORMANCE

Originally published in TrailerBoat #291 January / February 2013. Why not subscribe today?