The mid-1970s were an exciting time for GP racing. In ’75 ,Yamaha managed to steal the crown from MV Agusta before going on to claim back-to-back-to-back world titles in ’78, ’79, and ’80 – feats achieved by Kenny Roberts. By the dawn of the ’80s, the tuning fork company’s marketing department started kicking around the idea of introducing a high-performance road-bike derived from its half-liter, oil-burning TZ race platform.
In late ’83, Yamaha unveiled the RZ500, though it would be another year or two before the race replica became widely available. Also known as the RD500LC (Race Developed 500cc Liquid-Cooled), the V-4 had different monikers for different markets. Unfortunately, strict Environmental Protection Agency regulations in the US prevented America from being one of said markets, however a handful of enthusiasts have imported examples, many of which I assume from Canada, where the RZ was available.
Upon its release, the RZ500 was supposedly considered to be the very first bonafide grand prix replica. The RZ’s spec-sheet was pretty bonkers for its time, powered by a water-cooled, two-stroke, 50-degree V4 with dual crankshafts that red-lined at 10,000 rpm and put down a claimed 90 horses (at 9,500 rpm). The potent square-four inhaled via quad 26mm Mikuni carbs and exhaled through four expansion-chambered pipes — individually tuned for each cylinder — with Yamaha’s Power Valve System, which regulated exhaust timing via a variable valve that optimized timing in relation to each RPM level, allowing for more power.
Like Yamaha’s competition racer, the RZ’s V4 was paired with a removable cassette-style six-speed gearbox. The RZ was one of the earlier production models to sport a perimeter-style chassis too. The standard RZ’s frame was a steel unit, though the even more elite R-spec (RZV500R) boasted a hand-welded aluminum unit. Because of the lack of space under the seat, Yamaha’s engineers opted to mount the RZ’s (rising rate) rear suspension longitudinally and horizontally beneath the power-plant.
Despite being derived from Yamaha’s race program, the RZ’s suspension was seemingly a bit of a mess. Each fork leg featured hydraulic adjustable anti-dive units that were reportedly pretty ineffective (and reduced braking feel — a major problem on a bike known for unpredictably locking up). The RZ also featured a 16-inch wheel up front with an 18-incher in back, which, when combined with its 54-inch (1,374mm) wheelbase, reportedly resulted in unpredictable/wonky handling. Having said that, the RZ was apparently exceptionally stable at high speeds.
With these issues in mind, one enthusiast set out to iron out the kinks that Yamaha failed to sort before the RZ left the factory. Imported from Australia, this particular 1984 RZ500 example came into the current owner’s possession in 2012, before receiving a myriad of modern upgrades. The RZ’s stock front end was jettisoned in favor of an R6 unit — complete with 17-inch wheel — slotted in a custom triple. Out back the Yammy’s stock swingarm has been replaced with a 2010 R6 swinger — also with a 17-inch wheel — which has been paired with a new Works Performance monoshock. The braking hardware has also been overhauled.
At the heart of this example is a Bill Wilson “Faze 1” motor that now puts down a claimed 100 hp (ten more than stock). Bill Wilson is also responsible for the bike’s throttle junction, choke, oil-injection cable, and junction box. The four stock 26mm Mikuni carbs have been replaced by 28mm Mikuni flat slide units — all of which have been recently rebuilt and tuned. Other mechanical updates/upgrades include new radiator (and hoses), new CDI ignition, rebuilt YPVS box, and, my favorite, Jim Lomas stainless steel expansion chambers capped off with carbon silencers.
Though it looks mostly stock, this example’s cosmetics have gotten some attention. The frame’s been powder-coated, side and bottom panels have been repainted and braced, and the fuel-cell’s interior has been sand-blasted and coated. In an effort to further modernize this RZ, the owner opted to shod the R6 wheels in Pirelli Diablo Rosso Corsa rubber.
The RZ’s stock forks, swing-arm, and a handful of other factory parts are included in the sale, as is the factory owners manual. According to the seller, close to $30,000 has gone into this example, (seller has receipts), making the asking price a lot more reasonable. Since the engine’s rebuild, only 7,000 miles have been put on this example. I personally have mixed feelings about this example. On one hand, I feel like it’s a tad blasphemous to molest an elite classic like this, while on the other hand I can appreciate wanting to upgrade its performance (assuming it was purchased to be ridden).
You can find this upgraded 1984 Yamaha RZ500 (VIN: 53G004576) for sale here on Craigslist in Los Angeles, California with a price of $15,000.