Categories: Features Yamaha
31 | Updated 13

Duke’s Den: Yamaha RZ500 Two-Stroke Flashback!

Of the things we love most, we often think about things we grew to love in our formative years. This is often true for music, vacation destinations, loves, and, yes, motorcycles.

At least this is true for me. Of the nearly 900 different motorcycles I’ve put between my legs during my riding career, it’s Yamaha’s splendiferous RZ500 that shines brightest in my heart. In 1984, the RZ’s 500cc two-stroke V-4 mimicked the one in Kenny Roberts’ factory grand prix racebike, creating one of the first fully faired repli-racer streetbikes.

The RZ500, however, wasn’t legally available in the U.S., thanks to the ever-tightening noose of emissions regulations that kept two-stroke oil-burners like the RZ away from American consumption. This wasn’t a problem for me, though, as I grew up in Canada where two-smokers were welcomed – lots of trees and sparse population density up north, eh?

I had fallen in love with motorcycles by riding off-road, graduating to a Honda CR125R when the earth was cooling back in 1985. Meanwhile, a few friends were getting into streetbikes, and I began to envy how they could simply ride their motorcycles out of their garages instead of first strapping them down in the back of a truck or a trailer.

My buddies Ken and Dale offered up the gateway drugs. First was a Honda CB400F, followed shortly thereafter by two-smokers like Yamaha’s RD400 and Kawasaki’s KH400. The exciting power-delivery nature of the RD and KH was familiar to me, as I had only ever owned two-stroke dirtbikes. However, my parents warned me that purchasing a streetbike would result in a new residence outside their cozy basement I was living in, so I continued to sate my moto aspirations solely in the dirt.

Meantime, I took a spin on a friend’s Honda Interceptor 500, a wonderful four-stroke sportbike with a sweet V-4 engine. It was the most lovely machine I had ever piloted, and I lusted for it. But then I was able to get behind the handlebars of Ken’s latest bike, an RZ500, and my grand-prix fantasies kicked into high gear. Starting it was part of its theater, as its kickstart-only provisions were actually a luxury relative to a GP bike. When I heard it cackle to life after a swift kick, visions of Kenny Roberts danced through my head because I knew this machine was indeed something quite special.

The most exotic RZ500 is the RZV500R sold only in Japan. It employed an aluminum frame and upgraded suspension, but its engine was detuned to a 64-hp factory rating to meet domestic requirements, down significantly from the 87 hp claimed for export-market RZs. Anti-dive fork systems were in play; large brake rotors weren’t.

Spurting oily smoke from its pair of undertail stingers (perhaps the first such exhaust on a streetbike), the RZ looked like the racetrack refugee it pretended to be, aside from its headlight and fenders. It was a street-going replica of the YZR500 factory racer ridden by King Kenny during the 1983 GP season. Powered by a liquid-cooled 50-degree V-4 housed in a perimeter-style box-section frame, the RZ500 was a mid-1980s sport-rider’s wet dream.

With it’s twin-crank layout, the engine essentially functions as a pair of 180-degree parallel-Twins geared together. However it worked, the engine sounded glorious, with four cylinders spitting out a cacophony of racket that sounded like it was either going to blow up or rocket it into low-earth orbit. Its powerband is, at its low end, surprisingly docile, with less breathing of fire than might be expected despite its servo-controlled Yamaha Power Valve System system intended to bolster mid-range power. But get it up on its pipe – around 7000 rpm – and the V-4 lunges forward with an urgency that seems almost frighteningly supernatural. Although its 80 horsepower at the rear wheel seems almost quaint today, its power delivery is guaranteed to keep your attention!

Yamaha RZ500: The Grand Prix Fantasy

I simply had to have one. And that’s how a stupidly fast and barely predictable two-stroke GP-replica sportbike became my first street motorcycle. I highly recommend streetbike noobs begin with something a bit less savage!

Today, lo the decades that have passed, I vividly recall the feeling of holding on the throttle at only about 20% in second gear and just letting the revs climb without additional throttle input. Revs gathered sluggishly at first, more like a GT80 than a GP monster, gathering rpm slightly quicker as the tach needle ascended. And again. And at 6500 rpm but still with 20% throttle, revs leapfrogged over each other like a powerdrill and quickly induced wheelies without even trying, culminating in a crescendo of ring-a-ding noise screaming to 10,000 rpm that would make King Kenny proud. There is simply nothing else quite like it.

The hit of power from a two-stroke V-4 inspired this photo and, later, an “Imprudent Driving” infraction. Photo by Ian Johnston.

It is that intense and oddly mystical feeling I’m reminded of whenever I’m asked a motojournalist’s most frequently posed question: What’s your dream bike?

For me, it would be that invigorating V-4 engine stuffed inside a modern sportbike chassis. You see, for as wild and fun as the RZ500 is, its steel-framed chassis and odd wheel sizes weren’t able to measure up to its motor. This became more apparent in 1985, when Suzuki introduced its lighter aluminum-framed RG500 Gamma, despite the two four-cylinder two-stroke motors producing similar horsepower. Although I dreamed of my RZ-powered dream sportbike, the upward-trending prices of RZ500s have kept my dreams in fantasyland and out of reality.

MO Quiz: How Well Do You Know 1990s Two-Stroke Sportbikes?

My pretend world meshed with my real life a few weeks ago while at the Circuit of the Americas for a ride on BMW’s uber-superbike, the carbon-framed and -wheeled HP4 Race, which was the most capable sportbike I’d ever ridden. After my sessions were over, I strolled through the pits and ran across a close approximation of my dream machine, owned by my newest best friend, Paul Stamper.

2018 BMW HP4 Race First Ride Review +Video

Stamper sitting behind his aluminum-framed RZV500. The front two cylinders feed Jolly Moto expansion chambers exiting on the right side, while the rear cylinders fire into twin undertail exhaust pipes.

Stamper was attending the trackday with his RZV500R, a higher-spec Japanese-market RZ that used hand-welded aluminum for its box-section frame instead of the RZ’s steel chassis. Despite the bike’s exotic pedigree, Stamper made several comprehensive mods his RZ to make it more suitable for his trackday use.

The most obvious update is the adoption of Yamaha R6 suspension, swingarm, brakes and wheels, a major upgrade from the RZ’s twig-like 37mm fork (with flawed anti-dive system) and its oddball 16/18-inch front/rear wheels. The early-generation R6 components are steps behind the contemporary leading edge, but they are more than capable for the power and weight of the RZV. Stamper says the RZ’s lightly modded motor cranks out 90 horsepower to its tire, and the bike scales in at a tidy 360 pounds with its tank full.

Stamper’s RZV500 rolls on R6 running gear, with the R6 swingarm adapted to operate with the aftermarket adjustable shock mounted Buell-style under the engine as used in the stock bike.

My heartstrings were yanked mightily as Stamper walked me around his RZ. I couldn’t help imagining what it would be like to feel that two-stroke V-4 thrusting me around the marvelous COTA track, aided by brakes, suspension and tires that are generations ahead of the bike’s original moribund components. Stamper literally had the key to my dream.

It’s said that you create opportunities by asking for them, so I did. And Stamper graciously told me I was welcome to take his bike for a spin around the GP circuit!

My mind raced with anticipation as I hastily threw on my leathers while Stamper took his RZ out for a warm-up lap before handing it over to me. Would my lofty, nostalgia-tinted expectations be met, or would my blast from my past be a disappointing let-down after riding modern superbikes like the amazing $78,000 HP4 Race I had sampled just an hour earlier?

Stamper handing off his RZ to a rider whose dreams were coming true…

Hearing the RZ500 cackling in pit lane while I slipped on my gloves brought back a flood of memories from my long-ago formative years. It sounded just as awesome as I remembered, with a soft, snowmobile-like purr at idle that transforms into a shrieking high pitch at the blip of the throttle. Some might say that a two-stroke motor sounds unrefined relative to a four-cycle engine, and that might be true. But, to my ears, no other motorbike engine sounds as electrifying as the RZ’s.

Engaging the clutch reminded me of the RZ’s tall first gear, which made dragrace-style starts challenging on the street but would be no issue at COTA. The transmission swaps gears with a crudeness that would be unacceptable on a modern bike. These foibles, however, didn’t bother me in the least, as I was so thrilled to revisit familiar but distant feelings from the RZ. Even the seat, which is otherwise nearly inconsequential to a motorcycle, felt familiar to my butt cheeks, another reminder of the streetbike glory days from my youth.

A smile broader than Texas inside that helmet…

The stock RZ500s steer slower than many expect from a 500cc two-stroke, and Stamper’s wasn’t much different despite the altered geometry from his chassis mods. This inherent stability pays off in rider confidence, as the bike reassuringly didn’t feel sketchy in any way.

With COTA’s long backstraight in front of me after exiting a first-gear corner, I wound the nuts off the eager V-4 and was soon going faster than I ever did on my RZ. Acceleration forces were way below the 205-hp HP4, but they were much stronger than any production motorcycle displacing 500cc or less. In that moment, I felt like Kenny Roberts leading the Assen GP on his Yamaha.

Nearing the end of the straight, I had to guess when apply the brakes. I was probably about 50 mph shy of the HP4’s max velocity, but I also lacked the BMW’s incredible Brembos and wasn’t sure what to expect from the R6’s brakes. It turned out I had plenty of time to bleed off speed and backed off way before necessary, despite a two-stroke motor’s dearth of engine braking.

Knee down and grin up on the RZV500 at COTA.

The stadium section of the track was especially fun for me on the RZ, as the straights linking the corners were much longer than they were on the mega-powerful Beemer, so it allowed time to revel in the power delivery from the counterbalanced V-4 as it tach’d out just past 10,000 rpm. The RZV was confidence-inspiring while leaned over, and I flashed back to my first trackday aboard my old RZ when I could only aspire to drag my knee in corners like I was on this day.

After getting acquainted with the RZ on my out lap and not having it blow up or headshake me into a wall, I got more aggressive with my riding during my second lap and delighted in its unique feedback and faint familiarity. The HP4 Race was clearly much faster and abundantly more capable than Stamper’s RZV, but the smiles inside my helmet arrived twice as big and 10 times more frequent!

Stamper didn’t put a limit on the amount of laps I could ride, so I was determined to keep riding until the session ended or I ran the bike out of gas. Sadly, the RZ had exhausted its fuel tank as I neared the end of my second lap, forcing me to limp it back into the pits.

So, although my time aboard the RZV500 was incredibly brief, they were six of the most invigorating minutes I’ve ever had on a motorcycle. Sure, my experience was indelibly colored by rose-tinted nostalgia that brought back a flood of memories from my formative streetbike roots, but it was also a vivid reminder of the intoxicating nature of riding a GP-replica two-stroke motorcycle – a unique thrill for anyone, but especially to those who grew up idolizing racers like Roberts, Rainey, Spencer, Lawson and Schwantz.

“The bike puts a smile on my face every time it smokes out the four-strokes going into Turn 1 at start of day,” Stamper says about riding his RZ. “Even more enjoyment as the track comes in later in the day and I have the ability to run lines that the literbikes cannot hold. Corner speed makes up for all out speed, and it will run consistent 2:50 all day long at COTA with a 2:47 best. Going by Aprilia RSV4s and Panigales is just icing on the cake.”

Stamper aboard his RZV500R at Circuit of the Americas.

Adrenaline and excitement continued to sweep through my body for a long time after my ride on Stamper’s RZV500, which, for someone who has ridden all the best sportbikes in the past couple of decades, speaks volumes about the uncommon experience. Feeling the distinctive two-stroke powerband light up at the behest of my wrist to fire me around a modern GP circuit roused my moto soul in ways no other motorcycle could.

I’ll be eternally grateful to Paul Stamper for giving me the opportunity to ride his RZV and rekindle cherished memories while creating new ones. I’ve also called dibs for first right of refusal whenever Stamper decides to sell his bike…

The smile from dreams coming true.

Yamaha RZ500 Specifications
RZ500/RD500LC RZV500R
Engine Type 499cc 2-stroke, four-cylinder, liquid-cooled, reed-valve induction with YPVS
Bore and Stroke 56.4mm × 50.0mm (2.22 in. × 1.97 in.)
Fuel System Mikuni VM26SS 26mm carburetor x 4
Compression Ratio 6.6:1
Lubrication Yamaha Autolube two stroke injection, transmission gear pump.
Ignition Capacitor Discharge Ignition (CDI)
Transmission 6-speed, constant mesh
Final Drive 530 chain, 102 links
Front Suspension 37mm telescopic fork, non-adjustable spring preload, brake-linked anti-dive system 37mm telescopic, air-assisted fork, adjustable spring preload, adjustable rebound damping with brake-linked anti-dive system
Rear Suspension Link-type, gas/oil damped, 5-way adjustable spring preload, 4-way adjustable rebound damping
Front Brake Dual hydraulic disc
Rear Brake Single hydraulic disc
Front Tire 120/80-VR16
Rear Tire 130/80-VR18
Overall Length 2,085mm (82.1 in.)
Overall Width 705mm (27.8 in.)
Overall Height 1,14 mm (45.1 in.)
Ground Clearance 145mm (5.7 in.)
Wheelbase 1,375mm (54.1 in.)
Seat Height 780mm (30.7 in.)
Dry Weight 205 kg (452 lb) 196 kg (432 lb)
Fuel Capacity 22 L (5.8 US gal)