End of an era for older two-stroke technology

From midnight tonight, retail sales of showroom-new blue smokers that don’t have direct fuel-injection technology built into them are no more. It’s all down to changes to emissions laws for outdoor powered equipment that come into effect on July 1, 2020 that will ban them from sale.

However, the ban doesn’t cover a two-stroke engine already hanging off your transom, or one bought second-hand from the shop or privately.

The sales ban on the higher-pollution technology, as well as the shock loss of clean-burn technology specialist Evinrude, pretty much marks an end of the two-stroke era in Australia – only one retailer, Tohatsu, will continue to offer either a 90hp or 115hp two-stroke outboard engine that both meet the new emissions guidelines. Two-strokes wearing iconic brand names including OMC Johnson, Evinrude, Mariner and even the late arrival of Vortex, have been around since the dawn of the outboard engine in the early 1900s, and have since dominated Australia’s boating landscape for decades because of their cheapness and ability to produce plenty of power, yet remain relatively light compared with a four-stroke equivalent.

This is largely because the valveless two-stroke engines needed fewer moving parts than their four-stroke equivalents, and use oil in the fuel to lubricate the pistons rather than rely on a built-in oil supply.

The start of the demise of two-stroke outboard engines began in the late 1990s when changes to US emissions laws put pressure on manufacturers to develop cleaner-burning four-stroke technology for their marine products.

That’s not to say two-stroke technology hadn’t evolved to help with minimising emissions.

Two-stroke outboard engines went from pre-mixing the oil to injecting it into the fuel line, with the oil feed self-adjusting to feed in less oil at higher revs, and more oil at idle speeds.

Yamaha started playing around with direct injection technology for two-stroke outboard engines in 1999. The evolution started with the Z200N, a 200hp V6 that offered far superior fuel economy than existing direct-injection models.

This engine also had the unique ability to minimise the traditional two-stroke headshake at low revs by cutting the fuel flow to two of the cylinders while idling. The engine was also the first to include a self-diagnostics system that could detect a fault and limit the outboard engine’s performance – the so-called limp-home mode.

It’s only in recent years, though, that four-stroke outboard engine technology has been able to catch up with the weight advantage that kept two-stroke technology at the front of buyers’ minds.

Even as late as 2000, if you wanted big 135hp-plus performance from an outboard engine, you’d be looking at a two-stroker.

Yet anyone who grew up copping lungfuls of premix exhaust as the boat idled along with a following breeze behind it, or waiting in the water for the ski boat to take up the towrope slack before tapping the two-stroke’s strong hole-shot performance, will probably not shed a tear to see the sun set on these older engines.

If we do shed a tear for the good old carbie two-stroke, it’s more likely from the memory of smoke in our eyes than sentiment.