Two-Strokes Have Futures in PWC

The author experienced firsthand the performance of the agile and responsive Sea-Doo RX DI. (Photo by Robert Brown)

With the much-touted introduction of four-stroke engines in both Yamaha and Sea-Doo personal watercraft this year, it's easy to regard two-stroke engines — even direct-injection engines — as dated pieces of technology. Carbureted two-stroke motors have reputation (not undeserved) for being dirty when it comes emissions, and even the far-cleaner direct-injected two-strokes have too often been tarred with the same brush.

But if four-strokes are the future, why are PWC builders such as Bombardier, Kawasaki and Polaris still offering direct-injection two-strokes? A closer look at the 2002 Sea-Doo line of direct-injection product shows why the two-stroke may be enjoying a rebirth — and securing its place on the water.

Different Stroke

In 2000, Bombardier introduced the first personal watercraft with direct fuel injection on two models. Bombardier partnered with Orbital, an Australian engine builder to create a Rotax-engine-based, direct-injection motor for the GTX and RX watercraft.

The direct-injected two-stroke was the first significant step toward meeting Environmental Protection Agency emissions standards for 2006, as well as creating more efficient technology across the marine industry. By electronically controlling the amount, timing and mix of fuel and injecting the fuel directly into the cylinder seconds after the exhaust is ejected, a fatal flaw in the two-stroke was addressed. Manufacturer estimates indicated that these original direct-injection models were more than 70 percent cleaner and 30 percent more fuel-efficient.

Breed Refinement

The GTX DI is Sea-Doo's most luxurious direct-injected model.

Sea-Doo, Rotax and Orbital didn't team up on the GTX DI model and call it quits. Refinement of the product is continual and, according to the people at Sea-Doo, the 2002 Sea-Doo watercraft with Orbital Direct Injection are 28 percent cleaner than the original direct injection units — and they already meet EPA standards through 2006 and more-stringent California Air Resources Board standards through 2004. Compared to carbureted two-strokes, the Sea-Doo's 2002 direct-injection motors reduce emissions by 80 percent and increase in fuel efficiency by nearly 40 percent.

But the challenge wasn't just about cutting emissions and saving fuel. Two-stroke engines found a fine home in personal watercraft because of their outstanding power-to-weight ratios, which translated to snappy performance. Any significant performance losses would, frankly, translate to losses in watercraft sales, and that was nothing Sea-Doo and entire beleaguered PWC industry wanted.

The good news, at least in terms of the Sea-Doo products I test-rode at the company's late-August media event? Bombardier and Orbital have worked hard to get the most out the technology. The results are immediate throttle response, the noticeable lack of smoke, breath-taking acceleration and an impressively consistent powerband.

Across the Line

So what happens if use the same 130-horsepower, Rotax 951cc engine model with Orbital Direct Injection in three very different watercraft ranging from 600 to nearly 1000 pounds? Quite a bit — and all of it quite good — and that's exactly what Bombardier did with the Sea-Doo GTX DI, RX DI and LRV DI models.

The GTX DI (MSRP $8,799) has a new deck and hull that builds on an already stable and dry ride. With an added 6 inches in length and an increase in the full-V hull of 3 degrees, the new GTX DI is built for the cruiser and family. Although the watercraft loses a bit of its playfulness with its increased heft and deeper V, it's a solid choice for riders who want to stay dry.

On the wilder side, the Sea-Doo's RX DI (MSRP $8599) does a great job satisfying a wide range of riders. It can excite the most jaded marine journalist with its outstanding agility and acceleration, yet it is solid and predictable, and won't scare away novice riders. The more you want to do, the more this watercraft can do — but at a base level, it is as stable and true as they come.

The largest model in the Sea-Doo line, the LRV has surprisingly good power.

Finally, direct injection has even made it into the largest of the large — the Sea-Doo LRV DI (MSRP $9999). A hair less than 13 feet long and one meal short of 1,000 pounds, the Sea-Doo LRV DI makes the term personal watercraft a bit of an anachronism. The direct-injection, 130-horsepower motor helps move this behemoth loaded with four people at a respectable clip, and with 180 gallons of storage space you can bring plenty of gear. It won't win any drag races, but it is by far the most social platform in Sea-Doo's line.

Performance, midrange and full size — all in a cleaner, more efficient package? Sounds like the two-stroke may be heading for a second life. Here's to clean living.

Model Comparisons

Model Name	RX DI	GTX DI	LRV DI
Length	112.3"	130.4"	155.6"
Width	47.3"	48.1"	61.5"
Weight (dry)	606 pounds	705 pounds	960 pounds
Engine	130-hp, 951cc two-stroke two-cylinder Rotax Orbital DI with R.A.V.E.	130-hp, 951cc two-stroke two-cylinder Rotax Orbital DI with R.A.V.E.	130-hp, 951cc two-stroke two-cylinder Rotax Orbital DI with R.A.V.E.
Rider capacity	1-2	1-3	1-4
Fuel Capacity	15 gallons	15 gallons	25 gallons
Price	$8,599	$8,799	$9,999