When I first tested Yamaha's F60A in May 2001 I was impressed with its quiet, smooth operation and good throttle response for a carburetted four-stroke. Since then I've tested two more of these engines, and both provided a good blend of performance and fuel efficiency on two very different hulls.

But the Achilles Heel of the F60A has always been its four carburettors, which require careful balancing for smooth engine operation, and need re-jetting should the engine be run on Alpine lakes such as Eucumbene in the NSW Snowy Mountains. This requires fitting leaner jets and using vacuum gauges to balance the carbies. When the engine is operated at sea level, richer jets must be installed and the carbies re-balanced.

The sequential multipoint EFI of Yamaha's F60C overcomes this problem. It also provides better acceleration across the entire rev range; slightly lower trolling revs; and reduced servicing expenditure - because any engine faults can be quickly diagnosed using a laptop computer.

Yamaha Motor Australia's Danny Casey supplied Trailer Boat with an F60C mounted on a colour-matched Horizon 4750 Seabreeze bowrider for a full-day evaluation on Sydney's Hawkesbury River - one of my favourite boat-testing locations.

The demo engine started instantly hot or cold, warmed quickly from cold and never blew any oil smoke. Shifting into forward or reverse gear was more positive than the F60A because the engine maintains 700rpm in or out of gear. Vibration levels were on par across the rev range, but above 4000rpm the F60C was quieter due to the absence of carbie induction roar.

Spinning a 13in Yamaha prop and pushing a total of 800kg including three adults to simulate performance against its carburetted counterpart on a Quintrex 475 Freedom Sport carrying three adults and spinning a 12in prop, the demo F60C performed very well and had the edge for acceleration out of the hole when the throttle lever was "floored", with particularly strong pickup from 4000 revs.

The power trim and tilt worked quickly and quietly, and through full-lock figure-eight turns no prop ventilation occurred.

Speeds in the performance table were the average of two-way runs using a handheld Lowrance GPS, while fuel consumption was measured using Yamaha's own equipment.

The F60C trolled us at 4.5kmh on 800rpm using 0.9lt/h; planed at 23.5kmh on 3600; cruised at 31.0kmh on 4000rpm using 7.8lt/h; and averaged 51.0kmh at 5650rpm using 19.5lt/h.

Servicing the F60C is no more complex than the F60A. The engine-oil dipstick and canister oil filter are easily reached; any contaminates in the fuel filter are clearly seen; and the injectors are grouped together neatly on the fuel rail. Only the vapour separator behind the composite air-intake manifold tubes could be difficult to access.

Yamaha recommends servicing the F60C every 50 hours or six months after the first 10 hours. The waterpump impeller should be replaced every 100 hours or once a year when the camshaft drive belt (designed to last 1000 hours) should be checked for any damage.

Warranty is two years and the F60C complies with CARB 2008 exhaust emission requirements.

1 Dead Slow Troll
2 Clean plane
3 Economical cruise
4 Maximum cruise
5 Wide Open Throttle