Yamaha F100D Outboard Motor Review

Originally published in TrailerBoat #290 January 2013.

Since its Australian release more than a decade ago, the Yamaha F115A has always been a popular engine. It suits a wide range of trailerable hulls and, while no ball of fire, it does return good performance when correctly propped, without needing to re-mortgage the house to pay the fuel bill.

The standard multipoint EFI makes the Yamaha F100D engine far more user-friendly than the four-carbie Yamaha F115A and gives true turnkey starting, just like a fuel-injected car engine. Though the Yamaha F115A was reliable, the carbies were a hassle to tune and required the use of four vacuum gauges to balance them.

YAMAHA F100D

Yamaha Motor Australia may disagree with me, but according to my sources at Ford Australia (I was also a motoring writer for several years), the Yamaha F100D’s 1596cc four-cylinder DOHC powerhead is the same engine as used in the car manufacturer’s Fiesta, just upended with a dry sump to suit an outboard application. The Yamaha F00D outboard motor develops 98.7hp at 5500rpm with a wide-open throttle rev range of 5000-6000. It has a voltage-regulated 25A alternator, adequate for most on-board electronics.

At 2.31:1, the gear ratio is deeper than the F115A, useful for planing a hefty hull, and the bucket-and-shim valve clearance design eliminates checks for the first 400 hours, though withdrawing the camshafts is fairly time consuming. The toothed camshaft timing belt is designed to last 1000 hours, but should really be checked every 100 — the 16-valve engine is an interference design in which the valves could contact the piston crowns if the belt were to break.

The Yamaha F00D outboard’s 4.5L oil sump is big enough to absorb dilution from extended trolling operations between oil changes, with recommended servicing intervals of every 100 hours, or annually after the initial 20-hour check-up. The OEDA three-star F100D has a four-year recreational-usage warranty.

ON THE WATER

Mounted on a Haines Hunter 510 Breeze cuddy cabin and swinging a 19in stainless steel Yamaha prop, the review Yamaha F100D easily handled our 1250kg total displacement (including three adults). It started instantly when hot or cold, with no oil smoke appearing at any time, and idled smoothly in or out of gear.

The Yamaha remote-control box had a smooth progressive shifting action with barely a clunk into gear. And providing the anti-ventilation plate was kept at least three-quarters immersed, power astern was good — great for backing off sandbars when fishing estuaries.

Despite a piston displacement that’s eight per cent smaller than the Yamaha F115A, the F100D felt almost as powerful, though lacking a variable intake valve clearance meant it didn’t quite have the holeshot of newer-generation engines like the Honda BF90D. But the Yamaha F100D’s holeshot and mid-range performance was still adequate for crossing bars and getting the boat out of danger when required.

There were a couple of specific aspects that really impressed me: the engine’s ability to maintain a clean plane at 3500rpm while punching into 1m head seas; and the fact there was no prop ventilation and the engine maintained its rev range (without needing to open the throttle) when the Haines Hunter was put through tight figure-eight turns at 4000rpm.

Overall, the Yamaha F00D outboard motor was quiet, particularly at or near WOT, and very little vibration was transmitted through the hull across the entire rev range.

YAMAHA F100D PRICE

As of November 2012 longshaft Yamaha F100D outboards had a price of $13,928 RRP with a spare stainless steel propeller coming in at around $1000.

THE TRADE-A-BOAT VERDICT

Origins of the engine aside, the Yamaha F100D outboard motor is fairly unique because it slots neatly between the lighter BF90 and bulked-up F115A. It may not have the torque of the bigger-displacement Suzuki DF100, but then neither does it have the weight. And when it comes to valve clearance checks, withdrawing the camshafts from the top of the engine instead of from the bottom makes a big difference to the finances given servicing rates.

To put it bluntly, fitting a Yamaha F100D outboard engine is a bit like slipping a glycerine suppository up your back passage — it clears everything out and gives your boat its oomph back, which is really what we all want from our trailer boats, after all. Thanks to Terrace Boating, 2382 Pacific Highway, Heatherbrae, NSW 2324, (02) 4983 5600 terraceboating.com.au, for lending us the demo Yamaha F100D used in this test.  

YAMAHA F100D PERFORMANCE

COMPETING OUTBOARDS