The Yamaha YX600S Radian

Under the radar

| July/August 2009

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    1986 Yamaha YX600S Radian
  • nighthawkradar
    1986 Honda CB700SC Nighthawk
  • eliminatarradar
    1986 Kawasaki ZL600 Eliminator

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Years produced: 1986-1990 
Claimed power: 66hp @ 9,500rpm (56hp @ 9,500rpm/period test)
Top speed: 125mph (period test)
Engine type: 598cc DOHC, air-cooled inline four
Transmission: 6-speed/chain final drive
Weight: 436lb (wet)
Price then: $2,399 (1986)
Price now: $750-$1,850
MPG: 45-55

The mid-1980s were challenging times for the motorcycle industry. After years of double-digit growth, motorcycle manufacturers everywhere found themselves fighting a steep slide in sales, with little hope of a quick rebound. Faced with a changing and constricting market, Yamaha, like every company, took a long look at its products and considered how it should adapt to a new reality. Shedding the bikes that had carried it into the 1980s, the Hamamatsu-based company redefined its image with a new range of machines including the V-twin Viragos, the Maxim series, the Vision and the FJ series. In 1985, Yamaha hit two major home runs when it introduced the 5-valve FZ750 sport bike and the V-Max, a liquid-cooled, 1,200cc V-4 adrenalin rush that quickly became the new king of the strip and the street.

The new standard
It was in this environment that Yamaha rolled out the apparently all new (more on that in a moment) YX600 Radian for 1986. Although hailed as a new standard, stylistically it was sort of a Mini-Me to Mr. Max, with Max-like touches including chromed tops on its CV carbs, chromed plastic “velocity stacks,” chromed instrument pods, and 7-piece plastic bodywork (excepting the metal gas tank) clipped to a relatively low-slung chassis. Power came from an air-cooled, 598cc inline four exhausting through a stubby, chromed 4-into-2 exhaust system. A 6-speed transmission took care of shifting duties, while a chain delivered the Radian’s claimed 66hp to the rear wheel.

So what made it an “apparently” all new motorcycle? In as much as the Radian was a new model and something of a new look for Yamaha, there was very little on the YX that hadn’t already seen service on another Yamaha. For all its newness, the Radian was a parts room special, created by raiding the corporate parts bin and deftly combining bits and pieces until Yamaha’s engineers and stylists ended up with their desired result.

Using existing parts to create something new was hardly a fresh concept; manufacturers have been doing it forever, and still do. For one, it’s economical, enabling a manufacturer to use proven and — more importantly — paid for pieces. For another, it cuts development time enormously, since most of the bike already exists, its parts just waiting to get reassigned to a new whole.

In the Radian’s case, the engine was the tried and true 8-valve inline four used in the FJ600, but modified with 2mm smaller carburetors (30mm instead of 32mm) and other tweaks for better mid-range and low-end torque. The carburetor airbox was lifted from the 550 Maxim, as was the frame, which made sense as the FJ600 engine case was the same as the 550 Maxim, making the FJ600 mill a bolt-in proposition. Further, the aluminum grab rail on the seat tail was from the Fazer, as were the Radian’s tach and speedometer, headlight, taillight, mirrors and turn signals. The front disc brake rotors were from the RZ350 and the calipers from the FJ600, while the shifter was from the 550 Maxim. Outside of its bodywork, the only parts unique to the Radian were the front forks and rear shocks.

6/21/2015 8:13:56 AM

I have a 1986 radian yx600 myself it is a great bike plenty of power. i picked up the bike for 500 dollars and really no severe problems out of it.

wil cisneros
6/24/2009 7:17:51 PM

Back in 1991, I was ready to buy my first bike. A buddy of mine had a 1987 Radian, so of course the Radian was on my short lists of bikes I considered. I also thought about the Kawasaki EX500, but in the end, I got a good deal on a leftover '90 Radian. I still have the Radian, it's been in storage and/or the garage for ten years, until I find the time and money to bring it back to life. As a matter of fact, the Radian is the reason I subscribe to Motorcycle Classics, hoping to get all the pointers needed to revive my beloved Radian. Hey editors, how about a story about bringing a stored Radian back from ten years of storage. I've got the perfect bike that you can borrow.

November December Vintage Motorcycle Events

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