Suzuki DF30

King of carbies

And unusually, it has a single overhead camshaft driving three valves per cylinder instead of the two for the DF25 and below, and the four for the DF40 and above. It's also the most powerful outboard in the Suzuki four-stroke range to have carbies. All more powerful four-strokes have multipoint EFI that automatically alters the air/fuel ratios according to barometric pressure and ambient temperature to provide true turnkey starting.

The Achilles Heel of multi-carbie four strokes is the ability of most of them to go rapidly out of tune, necessitating time consuming re-balancing using individual vacuum gauges. But at least, according to service technicians, the DF30's carbies hold their tune well and are easy to adjust if tuning is needed.

Cold-starting, the DF30 is not as easy as its EFI counterparts and requires careful co-ordination of the electric chokes and fast idle warm-up lever. I must confess, I had a few problems starting the demo engine and, being so used to EFI and DFI engines, had forgotten about the variation in engine revs between neutral and forward or reverse. All EFI and DFI engines have the same revs in or out of gear.

The demo engine blew some oil smoke on cold starting but this was more likely due to my starting technique than the engine as, once warm, no oil smoke appeared at any time, nor was there an oil smell when backing upwind.

However, there's no doubt the DF30 is one of the better-performing and smoother-running four-strokes in its power range. It accelerates harder than Honda's 552cc BF30 and Tohatsu's 526cc MFS 30B which have similar piston displacements, and is also slightly smoother-running across the entire rev range but, because of the carbie induction roar, it's noisier than the Tohatsu at or near WOT. And because of its significantly greater piston displacement and more solid construction it's also heavier, 17.5kg more than the Honda and 12kg over the Tohatsu.

Mounted on a 4.3-metre Blue Fin 4.3 Discovery aluminium runabout and spinning a 12-inch pitch Suzuki alloy prop, the demo engine provided plenty of power on this hull. Pushing a total of 570kg, including two adults, and trolling at a steady 800rpm, the averages were 4.6kmh and 0.5lt/h. Providing the antiventilation plate was kept immersed, power astern was good and no cooling water starvation occurred.

A clean plane was achieved at 20.7kmh and 3700rpm, and cruising quietly at 4000rpm, the averages were 25.3kmh and 4.4lt/h, while through full-lock figure of eight turns at 4500rpm no prop ventilation occurred. The compact power trim/tilt unit worked quickly and quietly to provide us with the best leg trim according to hull speed and sea surface conditions. At my recommended maximum cruising revs of 5000 the average was 36.3kmh, and at WOT of 6150rpm the averages were 46.7kmh and 9.9lt/h where, despite the induction roar, we could still talk normally at the helm.

Servicing is straightforward with good access to the carbies and their balancing linkages, the bowl type filter (my local dealer fits an in-boat water-separating filter as standard), engine oil filter and sump level dipstick with separate filler plug. The large capacity sump will absorb oil sludging during extended trolling periods well between oil changes and a nice touch is the freshwater flushing port on the leg for cleaning the cooling water passages with a garden hose.

Also, to prevent chipping the paint on the cowl, the sealing ring is on the upper cowl instead of lower. Recommended servicing intervals are every 50 hours or six months after the initial 20-hour service where valve clearances should be checked. The waterpump impeller should be replaced every 100 hours or yearly.

The DF30 has an Aussie OEDA "2 Star" emission rating and two year warranty for recreational usage.