1983 Honda CX650 Turbo
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Basically a mini turbine, a turbocharger is powered by the engine’s own exhaust gases. Exhaust gases flowing through the turbo turn a small rotor, which in turn drives another rotor to deliver air under pressure to the intake manifold. This creates a denser air charge, allowing a larger fuel/air charge in each cylinder, and hence more power. The challenge is making the extra boost of power easily controllable. As one contemporary writer said about the Honda CX650T, “The power comes on so suddenly that you’d best be pointed in the desired direction, because THAT is where you’ll be heading with great alacrity.”
Art Friedman, then editor of Motorcyclist, says research showed a demand for turbos: “The riding public anticipated motorcycles that had the weight and response of a middleweight with the power of a liter bike, at a price that was somewhere in between. There was a lot of excitement around them.”
The first Honda turbo, the CX500TC, was announced in 1981 and appeared in 1982. It not only sported a turbocharger, but also a complex fuel injection system and a pair of onboard computers. Like all CXs, the engine was a stressed member of the frame, while the chassis sported an integrated fairing, a huge headlight, dual disc brakes in front and a single disc in the rear.
Yet despite Honda’s best efforts, bugs remained. Period testers found that, although the CX500 Turbo was blindingly fast on boost, easily reaching 125mph, it was expensive, thirsty and suffered from a phenomenon known as turbo lag, meaning it would hesitate before the turbo spooled up and sent it lunging ahead. Getting a CX500 around a set of twisties could be challenging.
Honda went back to the drawing board and came up with the CX650T for the 1983 model year. The engine was bumped up to 674cc and the compression ratio increased from 7.2:1 to 7.8:1. The computer controls were simplified and the gearing ratios were adjusted, with a wider gap between fourth and fifth. The result was a bike that, while equally impressive on boost, was a lot easier to ride when transitioning from off-boost to on-boost.
Riding the boost
Period testers and Ron Graf, the owner of our feature bike, agree that the turbo is at its best on secondary country roads with broad sweeping turns. “I was coming up [California] Highway 9 in front of a Kawasaki or Yamaha 1100,” Ron remembers. “I was letting it rip coming out of the corners. I came to a crossroads and parked the bike. The guy on the 1100 came running up to me, ‘What is it?’ he demanded. ‘You have this skinny rear tire and I couldn’t keep up with you!’”
Read Ron Graf's experience owning and riding a 1983 Honda CX500 Turbo
A Honda CX650 Turbo is not at its best when the road really narrows, however. Period testers found the bike’s high center of gravity and 573-pound wet weight made for a lot of work switch-backing up mountain roads.