Kawasaki ZRX1100

SUDA Kawasaki ZRX1100
We haven’t yet had a chance to throw a leg over Kawasaki’s, new to the States, ZRX1100, but we thought it might be fun to give you a taste of dessert before dinner and let you see a ZRX1100 that was modified by a shop in Japan. This naked bike has been available in Japan for two years now, so we thought you might appreciate learning about how others have had some fun hopping-up the thing. Here’s the scoop from our Japanese correspondent, Rick Williams. You might be surprised to see from where some of the hot parts came.
By Rick WilliamsThis year marks the American market release of Kawasaki’s ZRX1100 retro rocket, that brings back an aura of three-time 500cc Grand Prix motorcycle champion Eddie Lawson’s superbike heydays. But some of the world’s riders have been enjoying the ZRX for the past couple of years. And you know what that means. . . modified, beast bikes have already been born. Why leave things stock when you can change them?
In Japan, the ZRX takes its place in competition with the Honda CB1300, Yamaha XJR1300 and Suzuki GSF1200 (that’s Bandit to you gaijin) in the “there’s no such thing as too many ccs” naked-bike category. Thanks to the fact that the ZRX uses what’s basically a ZX-11 engine (called ZZR1100 in some parts of the world), saying that the ZRX has tremendous hop-up potential would be an understatement.
Takahisa stands proudly with his creation But don’t take my word for it…the pudding proof is this breathed-on ZRX1100 built by Japanese tuner/bike dealer, Suda Motorcycle Doctor. They’re sort of the “Muzzy of Japan” so Suda is quite famous in its own country. Suda is located in Machida, a little burg on the outskirts of Tokyo. The shop manager is a dude named Takahisa Suda, and he digs Kawasakis. Especially those of the breathed-on type.
After the Suda guys breathed on this ZRX1100 it achieved a 10,000 rpm reading of 158 horsepower at the rear wheel. Though Suda’s engine output looks radical on paper, that kind of power potential can be found in every ZRX, thanks to the plethora of ZX-11/ZZR1100 parts that have been available for many years. This bike’s heritage gives it an added bonus that the Yamaha XJR1300 and Honda CB1300 can’t brag about because their powerplants don’t have a long sportbike history. Only the Suzuki Bandit 1200, whose engine is derived from the bulletproof GSXR1100, can boast a range of proven performance parts equal to the ZRX1100.
Even in normal trim, the ZRX is no slouch. Take a stock ZRX1100, stick it on a dyno and you’ll get a reading of about 90 horsepower at the rear wheel. Not bad, but the real news is the machine’s 65-70 ft-pounds of torque. But then a stock bike’s performance is nowhere near that of the Suda shop’s bike.
A trip to the top-secret Kawasaki parts bin wasn’t necessary for this project; Suda took a simpler route. They started by chucking the stock pistons for some JE [That's an American company that specializes in making pistons for NASCAR.] 2-millimeter oversized models that pushed the ZRX’s 10.1-to-1 compression ratio up to 12-to-1. Then the Suda gang nixed the stock 36-millimeter constant-velocity Keihins and installed 39-millimeter FCR flatslide carbs, with no airbox or even air filters to block the airflow. A ZX-7 “wide load” radiator was installed to keep the increased heat under control. And ZX-11 cams — yep, bone stock ZX-11 cams — give the engine that nice “blat-blat” sound.
39mm FCR Flatslides
ZX-7 “wide load” radiator The exhaust gases are controlled by Suda’s own “Project 328″ full exhaust (the 328 is the serial number of their first big project bike, a ZX-11 they used to set a top-speed record at Bonneville in 1994 with an engine very similar to the one used in the ZRX). And a sturdy Fallicon [Yup, they're American, too.] crankshaft holds things together on the bottom end while ported heads and stronger valves make life exciting up top.
With all those high-performance goodies getting the job done, Suda also treated the engine with Microlon engine treatment for that metal-to-metal friction-fighting action that tuning gurus love
.The Suda ZRX’s suspension wasn’t overlooked either, with stiffer Race Tech fork springs together with that company’s patented Gold Valves providing performance that the soft stockers couldn’t match. “Those Gold Valves are an amazing invention,” says Takahisa. Out back, the twin KYB shocks were removed in favor of some super-stiff Dynamic shocks from Australia. Since this bike was targeted primarily for circuit use, the suspension is set up a bit too harsh for comfortable street riding.
This ZRX’s bodywork was custom painted a deep metallic blue, with the obligatory stickers applied to indicate all of the aftermarket parts inside. Neon-yellow “Suda Motorcycle Doctor” and white “IPTOS” (Improved Power Tuning On the Street) stickers are Suda’s very own stickers; if you see either of those, you know that the Suda shop’s touch is apparent somewhere.
Finally, Takahisa asked me the magical question: “Take it for a ride?” Let’s get it on. He popped out the four little cloth balls residing in the flatslides’ air intakes (no need to give any mischievous mice a place to deposit their belongings) and fired up the bike. The triple outlets of Suda’s designed-in-house Project 328 exhaust do a nice job keeping the decibels down; the bike just sits and idles peacefully without setting off any car alarms.
I swung onto the bike’s wide, comfy saddle, and moved out into the traffic. As I tooled down the road, I saw women and children run for cover as the sound of four unfiltered flatslides sucking wind filled the air with Darth Vader-like menace. “Braaap, braaap.” Feel the Force.
Finding an uncrowded little side street, I decided to see what this hooligan bike could do. Whacking the throttle in first gear, there was absolutely zero hesitation before the front wheel started climbing for the sky. Rear brake alert! Whoa, I backed way off. I thought I’d try that in second gear instead, I didn’t want to loop this thing.
Whack. Again no hesitation, except this time the front wheel didn’t come up as fast. It still looked at the clouds, but it just arrived in the up position at a more leisurely pace. Third gear? More wheelie action, but finally in a manner I could easily control. Yep, I like this third gear, it makes life easy. And oh my stars. . . how can carburetors work that well? No dips, flat spots, or downward spirals in the power curve. Just sheer power that builds like a dynamo, daring you to give it a little more.
I’ve ridden three different stock ZRX1100s in a variety of riding conditions, and none could match the stability of Suda’s ZRX when it comes to taut suspension. I wish I’d had a chance to wing it on a track with this bike, the potholes of Machida were a bit hard on me because of this bike’s uncompromising suspension settings (again, this bike was set up for circuit use).
When I finally tired of wheelies ‘n whiplash, I headed back to the Suda shop. As I dismounted, I realized that my left elbow was actually sore from the ultra, leap-forward effect of the machine. This ZRX1100 features Suda’s “Stage 4″ kit for the 158-hp reading. Suda also offers a less-gnarly version called “Stage 2″ (Suda ain’t got no “Stage 3″… just like that guy in Spinal Tap, “4 is better than 3.”). The “Stage 2″ kit still gets the flatslides and oversized pistons, but retains the stock cams, pushing the power up to around 140-hp at the rear wheel. A “Stage 1″ kit is offered for those not willing to rip up the pavement, consisting of basic airbox/jetting mods for a 6-8 horsepower increase over a stock ZRX.
Just for kicks, the Suda guys once ordered up some lighter pistons and camshafts offering musclecar-like lift and duration, and recorded a 165-horsepower reading on Suda’s Dynojet dynomometer with that ZRX engine. Boys and toys. . . it doesn’t matter what country you’re from, we all like to play.
Suda’s experience in 1994 with their ZX-11 top-speed pursuit gave them the knowledge they needed to transform the Kawasaki ZRX1100. But why build a naked bike? “A lot of Japanese riders like naked bikes,” said Takahisa. “They are very comfortable bikes, so you can use them to go touring to the mountains as well as riding around on city streets. And many owners like tuning to get high power. We knew the power was there, it was very easy for us to build this bike. It’s almost the same engine as the ZX-11, and parts are very easy to find.”
So how do you say “more power please” in Japanese? It might not show up in an English-Japanese dictionary, but I think the answer to that question could be, “Dr. Suda.”
And now the ZRX is set to invade America… let the hot-rodding begin!
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