Kawasaki ZRX1100 Setup Tips by Jim Gianatsis with Rob Muzzy, Al Ludington

Eddie Lawson rode a Rob Muzzy prepared Kawasaki KZ1000R to victory in the 1982 AMA Superbike Championship. Eddie's teamate on the US factory team that year was a kid named Wayne Rainey. Both Eddie and Wayne would go on to win the 500cc World Grand Prix Championship for Yamaha. But that season I had the privilege season of being the race suspension engineer for Fox Shox, working with and setting up the Fox Shox on Eddie's AMA National Championship winning Kawasaki, and the other top factory Superbikes that season from Honda and Yoshimura Suzuki.

Kawasaki's introduction of the new replica ZRX11000 is a tribute to that classic KZ1000R Superbike of days gone by, but with updates derived from contemporary sportbikes. Gone is the aircooled KZ engine, replaced by the more modern, but detuned motor from the current ZX-11. The latest 6-piston Tokico sportbike brakes makes this Kowie stop on a dime despite its hefty 490 lb. dry weight (545 lbs. wet!). The trick braced alloy swingarm with it's concentric axle/chain adjuster is a beautiful finishing touch.

I had to have a ZRX for my own the moment I saw pictures of it. I had been longing for ane old sit-up non-faired sportbike from the early '80s that could ride 2-up and the ZRX fit the bill perfect, especially at the low $7,200 price tag.

IMPROVING HANDLING
The ZRX has no major inadequices and can be ridden hard, just as is right out of the crate. On tight canyon roads like those around Los Angeles, the bike's quick steering geometry and wide bars make it a very responsive handling, conifedence inspiring mount that can run with more modern bikes like a Ducati 996 and Yamaha YR1.

When the roads are rough, though, the stock Kayaba piggyback shocks really show their shortcommings. Despite separate extenal compression and rebound adjustment knobs, the Kayaba's just don't work well in any setting, proving too much compression damping and not enough rebound. Together with an an excessivley heavy spring rate that offers no rear suspension sag (you need 30%) and kicks like a bucking bronco even at the lowest spring preload setting.

The availability of race quality replacement aftermarket shocks for the ZRX is limited here in America. So I had my stock Kayabas revalved by DeWayne Jones who did a great job although somewhat pricey at $350/pr because the damping pistons do sneed to be reworked.

You'll also probably need new rear springs. The stock ZRX springs are rated at 150 lbs which is great for riding 2-up with a combined weight of 300 lbs, but not for a single 180 lb rider. A single rider needs to run 115-125 lb springs. Ask DeWayne if he can set you up springs as well. You'll need 8-9" length springs, 1.88" I.D., 115-125 lbs. At present the only spring company offering such a spring is Eibach. No motorcycle suspension company stocks replacement springs that fit the ZRX's large diameter preload adjuster. Thank you Kayaba!

The Eibach spring you'll need is Part No. 0800.188.0125
This is a 125 lb. 8" tall spring. Because it is 1' shorter than the 9" stock 150 lb. Kayaba spring it replaces, thereisn't enough prelad adjustment available on the shock to take up the missing length. Works Performance offersan alloy 0.5" spacer to get you back into the ballpark for useable prelaod adjustement. Works Performance can order the Eibach springs for you and provide the needed spacers with one phone call to them. Eibach will not sell retail direct to you.

If you want to go first class, contact an Ohlins dealer and spend the bucks to get a pair of real roadracing shocks. Ohlins are the only brand I can recommend for new twin shocks at present. Non-adjustable sets will cost about $800 per pair, and the externally adjustable about $1200. Unfortunatley, no one in the US is stocking them and they need to be ordered from Sweden with a 6 week wait. Unfortunatly, Fox Shox no longer offers twin shocks for the streetbike market.

Otherwise everything else works great, the brakes, the forks. I don't recommend spending money on revalving the front forks, because any perceived problem at the front is being cause by the stock shocks/springs in back. Don't spend any money on a steering damper because it doesn't need it, especially once you get the rear suspension ride height lowered, which will rake out the front end more and slow down the steering.

Al Ludington, Miguel DuHamel's former tuner at Honda, and now at Team Kawasaki has a ZXR of his own. And Al recommends quickening up the steering by making sure the rear axle is positioned at the bottom of the concentric chain adjuster at the back of the swimgarm to give the bike more rake, but I don't think it needs it. The steering is quick enough with the axle positioned at the top of the adjuster.

Step #2 in saving weight and improving handling is to get a set of magnesium wheels with matching Supersport spec tires. A 6.00x17 Marvic or Marchesini rim out back (5.00x17 aluminum rim is standard) will save you 10 lbs., and a 3.75x17 up front (3.50x17 std.) will save you 5 lbs. more. But to be honest, th eZXR handles well enoughl with the stock wheels and Bridgestone rim protectors, and because I use it as a Sunday fun bike and weekday errand runner, I haven't been motivated to part with $2, 000 for race spec wheels and tires.

IMPROVING POWER
The only disapointment with a potentially even better bike is that Kawasaki couldn't leave the basic ZX11 engine alone. They detuned it for the ZRX with milder cams, a compression ratio lowered from 11:0:1 to 10.0:1, reducing carburetor size from 40mm to 36mm, and in turn droping peak horsepower down from 131 HP to 96, a decrease of 35 HP in the aim to build a more tractable motor. But the real blow came in droping one cog out of the transmission, changing it from a 6-speed to a 5-speed. The engine's broad torque curve doesn't really needanother gear when you're rowing throught the lower cogs, but every time I click into 5th on an open road feel rev the engine out, I shift for another gear that just isn't there.

Ironically, Kawasaki could have put the ZX11 motor into the ZXR and lowered production costs on both bikes, since it costs more money to build the same engine with 2 different sets of specifications and parts, than just one engine alone. Not to mention the ZX11 engine was C.A.R.B. approved for sale in California, which the detuned ZRX is not. Go figure. But we Californians know how to get what we want, anyway.

The first place to begin any engine modification is at the exhaust system. This reduces weight for better handling and improves the bike's power to weight ratio for better braking and acceleration.

The stock ZRX exhaust system weighs 30 pounds! A call to Doug Myer at Muzzy's got us a beautiful Muzzy 4-2-1 stainless steel header system tipped with a race style carbon fiber canister that weighed just 10 lbs. complete -a massive 20 pound weight savings.

Just bolting on the exhaust without any jetting changes, the bike ran great, if not perhaps slightly rich, and picked up approximately 5 HP. But shim down down the carb needles 1/2 clip, or buy a Factory or Dyno Jetting Kit and you're looking at another 5 HP increase -now up to 105 HP from 96.

The next step in affordable tuning modifications is to drop in a set of stock ZX11 cams from your friendly Kawasaki dealer. With cams and the right rejetting again, you're looking at between 124 - 130 HP at the rear wheel. Muzzy's website now offers a complete dyno breakdown of what power gains you can pick up with different jetting, pipe, air cleaner, airbox and camsfaft changes. This is the best place to begin with your tuning mods. Just removing the stock airbox silencer will gain 5 hp!
Visit http://www.muzzys.com/zrxdyno/index.html .

But with the ZX11 based engine the sky's the limit when it comes to making power. Send your motor to Muzzy and he can have it cranking out 170+ horsepoer the next time you see it again. or if you'ld like to have a 6-speed gearbox, maybe buying a complete ZX11 engine out of a wrecked bike at salvage yard is a more cost effective place to start. Just keep in mind the ZX11's downdraft carbs won't work in the ZXR's chassis and you'll need to keep the ZXR's sidedraft heads with sidedraft carburetors.

For more information give Muzzy Racing a call and visit their website at this link:

• MUZZY RACING, USA • Phone 1.541.385.0706

• TSUKIGI RACING
Japan's top parts manufactuer and racing team specializing in Kawasaki for the Japanese NK-1 "Naked Bike" Championship.
JAPAN • Fax 011.81.724.47.0648
USA • Contact Poncho Rangel • Phone 562-201-0038
TsukigiRacingUSA@aol.com