Honda NT650 Hawk GT Service Manual (1988-1991)

Honda introduced the Hawk GT in the United States for 1988 as a deliberately different kind of sport motorcycle. Instead of following the fully faired race-replica trend, Honda combined modern chassis technology with an exposed V-twin and upright, practical proportions. In its June 1988 road test, Cycle World described the bike as Honda’s response to riders asking for simpler, more rational motorcycles, while still emphasizing that it was a modern sportbike rather than a traditional standard.

The U.S.-market NT650 was closely related to Honda’s Japanese-market BROS Product One, type RC31. Honda’s original BROS development brief explains that the project began with the goal of creating a light, simple and slim road sport motorcycle that emphasized the basic enjoyment of riding rather than fitting an established category. The 647 cm³ liquid-cooled 52-degree V-twin was tuned for strong low- and midrange response, while the compact engine layout helped keep the motorcycle narrow and accessible.

The chassis was unusually sophisticated for an unfaired middleweight. Honda used a rigid aluminum twin-tube frame and its Pro-Arm single-sided rear suspension, technology associated at the time with much more specialized sporting machines. Honda’s factory chassis description specifically highlighted the aluminum frame, 41 mm fork and Pro-Arm, noting that the single-sided system had previously appeared on models such as the VFR400R and RC30. Combined with 17-inch wheels and hydraulic disc brakes at both ends, the result was a distinctive single-sided-swingarm V-twin sportbike built around usable road performance rather than racing bodywork.

The engine itself developed from Honda’s earlier 52-degree V-twin family. Cycle World reported that the Hawk’s powerplant traced its lineage to the VT500 Ascot, but Honda experimented with several larger capacities before settling on 647 cm³ for the new model. The production engine used a 79 mm bore, 66 mm stroke, three valves per cylinder and liquid cooling. In Japan, the related BROS Product One received a further update in 1990 with revised ignition, suspension settings and running gear, documented in Honda’s 1990 BROS release. The Hawk GT remained the U.S. expression of the same RC31 concept through the 1991 model year.

This factory service publication explicitly covers the 1988-1991 NT650 Hawk GT and includes both 49-state and California-specific procedures where applicable. It was originally issued in September 1988 and revised through June 1991. Related documentation is available in the Honda Hawk GT service manual catalog.