Retro or Not(ro)? Kawasaki Z900RS Vs. Suzuki GSX-S1000Z

They’re both Open-class Japanese transverse inline four-cylinder standard bikes, a pair of motorcycles that have followed that divinely ordained orthodoxy since Saint Soichiro carried the streetbike tablets down from Mount Fuji nearly 50 years ago. One of them wants to transport you all the way back to relive that era; the other wants to take you back only ten years with its 2005 GSX-R-derived long-stroke engine. Many MO readers (and some MO writers) have already pledged their undying love for the Kawasaki Z900RS, and all of us agree the Suzuki GSX-S1000Z is no slouch. In fact, if horsepower is your measuring stick, the Suzuki buries the retro Kawasaki – but you have to work for it a bit more. Our question becomes, then, just how much performance are you giving up if you go retro, and is it worth it in the real world?

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Take it away, Brent Jaswinski: Sitting next to each other, the Suzuki GSX-S1000Z and Kawasaki Z900RS may visually seem like two very different bikes. And while their unique appearances certainly differentiate them, a look at the bikes’ spec sheets tells us they’re not as dissimilar as one might think. They’re both liter bikes – well, the Z900RS’ motor displaces 948cc, but for argument’s sake we’ll round up: 948cc is more than plenty for streetability, after all… they’re both priced at $11,000 (our rootbeer Kawi is $200 more), they both have inverted front ends raked at 25 degrees (3.9 inches trail for the Suzuki, 3.5 in. for the Kawi) with radially-mounted brakes, 4.5-gallon fuel tanks, a weight difference of just 10 pounds – and they’re both a blast to ride. Both bikes have also been accused of having less than ideal fueling issues, which puts them in the same boat.

Live With It: 2018 Kawasaki Z900RS Long Term Review

Live With It: 2018 Suzuki GSX-S1000Z Long Term Review

Hopping off the RS and getting on the GSX-S, I immediately noticed the sportier ergonomics of the Suzuki. The footpegs are higher, the bars are a little lower, further forward and also narrower compared to the tall, wide and more relaxed rider triangle of the RS. Does this mean you can ride or push the Suzuki harder than the Kawi? Mmm, kind of.

Both motors have great character and pull hard. The Z900RS signs off a little earlier than the GSX-S1000Z, but the Kawi’s midrange is really punchy, compared to the revvier top-end hit of the ’Zuk. The Suzuki’s midrange is nothing to sneer at, but the upper revs are where the GSX-S starts to pull away from the RS, in straight line applications. It’s in the corners where the GSX-S truly has a leg up (pun intended) on the Z900RS, but not because of its horsepower advantage.

John B: In fact, if you didn’t have the dyno charts to look at, you wouldn’t really know there was such a discrepancy in the horsepower department. If speed is your thing and you live in Kansas, or only ride at the dragstrip, the Suzuki is your motorcycle. Its 134 horsepower buries the Kawasaki’s 97, but the Kawasaki reaches its peak at just 8600 rpm to the Suzuki’s 10,200 rpm.

In town, and on the tight curvy roads we like best, it’s all about the torque. Well, the Suzuki makes more torque too, but its 72.5 ft-lb doesn’t happen till 9300 rpm. Meanwhile, the Kawasaki’s making its peak at 6500 rpm – right where the Suzuki’s torque curve is all concave. That 5 to 8,000 rpm range is what we use most on our favorite roads. The Suzuki simply can’t exploit its horsepower advantage until the road really opens up, or the rider just screams its engine the whole time – which usually feels like too much work and causes too much drivetrain herky-jerky. The smooth linearity of the Kawasaki’s engine also makes it feel more powerful than it is.

Brent: The Kawasaki’s more relaxed, lower footpegs come into contact with the ground much sooner than the Suzuki’s, and that’s really the only place where I feel the GSX-S truly out-sports the RS. The Suzuki’s suspension is also firmer than the Kawi’s, which allows you to rail turns with precision. Our bad, however, that we didn’t mess with the Kawasaki’s clickers or rear preload to combat this, as we simply didn’t have the tools handy. We didn’t notice the rear preload was nearly all the way soft until we were on top of the mountaintop. Cranking in preload would’ve kept the pegs from scraping so much, and quickened the steering. I was still able to ride the RS with plenty of ferocity to keep competitive with the slightly sportier Suzuki. Dialing in the RS’ suspension and installing higher rearsets would practically eliminate any advantage the Gixxus has in the twists.

JB: True that. Speaking of footpegs, they too define roles: The Kawasaki has fat rubber ones from the Dr. Scholl’s catalog, the Suzuki gets racy knurled aluminum ones in anodized black. The Kawi’s pegs complement its more relaxed ergos, and when the road gets tight, it’s those ergos and its softer springing that keep the Kawasaki from transitioning from side to side quite as quickly as the Suzuki. Still, you have to dial the aggression level up to about 8 before there’s anything in it at all. By the end of our day when we were feeling our oats, I could keep up with Brent if he was on the Kawasaki, but he’d pull gradually away from me when he was on the Suzuki – riding deeper into the corners with the brakes on, throwing the Suzuki more rudely and farther onto its side, screaming it more often a gear lower. The Suzuki’s excellent gearbox makes easy work of that (but higher rpm exacerbates its slight remaining on-the-gas abruptness).

Brent: Both bikes have radially-mounted brakes. The Suzuki’s newly improved Brembo calipers work a little better than the Kawi’s until the ’Zuk’s ABS kicks in, but the Z900RS’ binders work great too, with plenty of mph-slashing power. ABS is standard on both, with my nod going to the Kawasaki’s system. The RS’ ABS felt a little less intrusive and abrupt when actuating, and it also lets you really pull and continue to hold the lever firmly under hard braking as opposed to the more pulsating feel of the Suzuki.

JB: Safely back at the bottom of our winding mountain road test circuit, yes, we deduced that the Suzuki is a better tool for unwinding it – but not by as wide a margin as we’d suspected at the beginning of the day. With a bit of judicious tuning (including a thing as simple as giving the Z900RS more rear spring preload), there wouldn’t be much of a performance gap at all. Again, if straightline performance is your thing, the Suzuki’s 134 horses will bury the poor Kawasaki – but if straightline performance is your thing, you’re probably not shopping either of these bikes. Find a nice used ZX-14R.

Brent: For all day, everyday comfort, ease of use and around-town practicality, the Z900RS works better for me. The seat is super comfortable and really another suspension system in itself. The helmet lock is something that should be standard on ALL motorcycles. I also preferred the gauges and LCD screen on the Kawi to the Suzuki. The analog tach and speedo look great while simultaneously providing the rider with all pertinent info at a quick glance; the needles on both read 6,000 rpm and 75 mph when completely vertical – perfect for letting you know when you’re breaking the law. Also for letting you know you’re right in the meat of the torque curve, but you’ll feel that through your ass.

And finally, when it comes to looks, the Kawasaki Z900RS just plain knocks it out of the park compared to the Suzuki. Never have I ridden a bike that has gotten more looks and compliments than the Z900RS, from older and younger people as well as riders and non-riders alike. It’s got great, classically inspired lines and a beautiful two-tone paint scheme that really pops with the subtle use of metal flake. The Gixxus is matte black… so 2011. It’s also somewhat plastic-y for my taste. Where the Z900RS gives up a little performance to the GSX-S1000Z, it more than makes up for in looks. With a little massaging in key areas, the Z900RS can be as sporty as the GSX-S1000Z.

JB: I can’t disagree with any of that, and would add that, back in the world of potholes and the ubiquitous “pavement irregularities,” the Kawasaki absorbs more of them more gracefully than the stiffer-suspended GSX-S – not that the Suzuki is that bad. For lots of freeway flogging, smaller riders might prefer the Suzuki’s sportier, more-tucked in ergonomics. But larger riders won’t, and all riders with bum knees, sore backs, hip dysplasia, limp wrists, and general malaise will appreciate the Kawasaki’s more upright seating, comfier perch and increased legroom.

In the final analysis, they’re apples and oranges, but we’re big fans of both fruits. When young Brent and I punched our opinions into the official MO Scorecard, the results it spat out were 0.16% separated – the Kawasaki taking the win in a photo finish. Both are great, ride ’em every day, wherever you need to be motorcycles. Again, if you know people who are going to talk you into a day at Chuckwalla or Road Atlanta, the stiffer, way-more powerful son-of-GSX-R Suzuki is the clear choice (and would actually be a lot of fun around the track). But for the way we ride 97% of the time around here, going retro means giving up very little real-world performance.

That’s it, we’re all out of Z900RS stories. Where’s our Honda CB1000R?