Kawasaki ER-6n vs. Suzuki Gladius: Six of one, half dozen of another

Though Kawasaki’s ER-6n has been available in Europe since 2006, it’s finally made it to U.S. shores in a newly revised form for 2009. The ER is the fraternal twin to the Ninja 650R, the bike the U.S. got in 2006 and is also updated for ’09. It shares identical chassis and engine specs (just as they did in ‘06) to the Ninja but does away with virtually all bodywork, save for minimalist radiator shrouds that house turn signals, and a prominent headlamp that functions somewhat like a flyscreen.

This year marks the first revision to both the ER-6n and Ninja 650R. In our review of the 2009 ER, Kevin “Canadian Bacon” Duke, educated us with the news that Kawasaki smoothed out engine vibes inherent in the parallel-Twin engine architecture. Team Green reduced buzz by way of rubber bushings in the upper-rear engine mounts, rubber mounts for the steel handlebar, rubber-covered footpegs, and even included rubber mounts for the pillion grab rails. Other updates include revised frame stiffness, a lighter catalytic converter, and reshaped fuel tank and seat that are more welcoming of shorter riders. The Ninja 650R also received updated bodywork styling, and both bikes share a new instrument cluster.

Whether by a need to capitalize on shifting market trends or some other undisclosed logic, Suzuki laid to rest the venerable SV650, a bike that quickly reached cult status after its 1999 introduction. Oh, the wailing and gnashing of teeth that must’ve happened amongst the Suzuki loyal when they learned the naked SV650 was no more for 2009 (a fully faired SV650SF remains in the lineup at $6,999). Although Suzuki refuses to refer to the 2009 Gladius as a “replacement” for the SV650, the fact that the Gladius is powered by a revised and updated V-Twin that made the SV so popular makes it hard not to see this new naked sportster as an SV reborn.
We learned during the Gladius’ U.S. press introduction that its 90-degree V-Twin sees numerous improvements in the engine room with things like: higher lift cams; single rather than dual valve springs; the same 10-hole injector throttle bodies as found on the GSX-R600 and 750; longer air intake funnels in two different lengths for improved mid-range; use of Suzuki’s Idle Speed Control (ISC) system integrated into the throttle body rather than externally mounted – a first ever on any Suzuki street bike; a new compact mid-ship exhaust (similar to the ER’s); two Iridium-tip spark plugs per cylinder complete the engine update package.

Carrying the capable engine is the work of a truly new-for-the-Gladius steel-tube trellis-type frame mated to a box-section steel swingarm. The styling of this new middleweight is purely unfaired with only two small accent pieces dressing up a re-designed radiator, and a headlight and instrument panel styled together make for a look equally unique but different from the ER-6n.
Two peas in a pod

Both bikes are liquid-cooled, DOHC, 4-valve-per-cylinder, and both are called a 650 by their respective makers, but the ER squeezes out a skosh more in displacement at 649cc (83.0 x 60.0mm) in its parallel-Twin, while the Suzuki’s 90-degree Vee is a true 645cc (81.0 x 62.6mm). Compression ratios are scary close, too, with the ER at 11.3:1 and the Gladius with 11.5:1. But the similarities don’t end there…
There are two different types of engines at work here, but a quick scan of dyno results courtesy of Mickey Cohen Motorsports will make you do a double take. The graphic representation of horsepower and torque looks almost as if one bike was dyno’d twice. It’s a neck and neck race in hp, as both bikes are amazingly well-matched until about the 7,400 rpm range where the Gladius starts sprinting for a peak hp reading of 67.9 at 8,500 rpm, a full 5 more peak hp than the ER. The differences in peak torque are even closer, separated by just a hair over one foot-pound (44.2 v. 43.1 ft-lbs) in favor of the Gladius, but more important here is that the ER hangs tight until the last minute, as you can see by the dyno chart.

The numbers game is almost too close to call at times, but engine character is a different story. The Gladius’ Vee configuration provides that traditional grunty bottom-end feel, while the (mostly) vertical action of the Kawi’s side-by-side pistons gives the impression of a revy in-line sportbike motor. Neither of these bikes will leave 99% of their owners pining for more power. Both wheelie first gear easily with a little finessing of the clutch and will dig you out of a slow corner in no time.

Fueling and throttle response are good on both motorcycles, however, the ER exhibits a “hint of abruptness during throttle reapplication,” as Kevin dutifully points out, but then smoothes out immediately thereafter. Transmission and clutch action is more of the same. The ER’s trouble-free six-speed uses Kawasaki’s neutral-finder design that eases access to neutral when stopped, and rowing through the slick Suzi gearbox is a shifting pleasure.