Honda GB500 TT Tourist Trophy 1989-1990 Service Manual

Rider Magazine's own retrospective confirms the genuine cultural motivation behind this bike's creation: "in 1987 Soichiro Honda was still exhorting his minions to come up with new product... For all we know, this might have been Mr. Honda's own notion, as he had a great respect for the once-great British motorcycle industry... The GB500 was as much a styling exercise as anything else, made to look like a machine one might have seen on the Isle of Man during TT race week. The official name of the motorcycle was 'Tourist Trophy,' spelled out with decals on both side covers." Iconic Motorbike Auctions' own retrospective confirms the genuine irony at the heart of this bike's appeal — quoting Cycle World's Peter Egan's own contemporary verdict: "simplicity and grace are never out of style, and the GB is a simple, handsome bike. It's not a Velocette Venom Clubman, but I don't care. We already have Venom Clubmen if we want them. This is a new motorcycle that looks good and is fun to ride, and there are never enough of those."

Power comes from a 498cc air-cooled SOHC single, 4 valves per cylinder, a genuinely oversquare 92mm bore and 75mm stroke, and an 8.9:1 compression ratio, delivering a claimed 38 hp at 7,000 rpm (measured at 33-33.3 hp at the rear wheel) and roughly 26.3 lb-ft (35.6 Nm) of torque at 6,000 rpm through a 5-speed transmission with wet multi-plate coil-spring clutch and chain final drive, fed by a Keihin PH69 carburetor with CDI ignition and electric starting. Hagerty's own detailed engineering account confirms this radial-valve single's real mechanical lineage: "the radial-valve 498cc single was based on the dry-sump, radial valve XL600 enduro motor, connected to a smooth five-speed gearbox" — genuinely proven off-road engine architecture repurposed and refined into a dedicated café-racer application. Motorcycle Classics' own detailed technical account confirms the deliberate stylistic engineering choices that gave this Japanese engine authentic British character: "the Brits like cylinders with roughly equal dimensions, the Gold Star having an 85mm bore and 88mm stroke, the Venom a perfectly square 86/86, while the Honda ran a short-stroke, oversquare cylinder" — a genuine technical departure from the classic bikes it was styled to evoke, even while everything visible above the cases was designed to look period-correct.

Motorcycle Classics' own detailed styling account confirms genuine period-correct detailing throughout: "the oil tank lives behind the right side panel (thoughtfully stenciled 'Tourist Trophy') and the whole is wrapped in a single downtube dual-cradle steel frame. An aluminum box-section swingarm holds the spoked rear wheel with traditional dual shock suspension... narrow 90/90 x 18in front and 110/90 x 18in rear tires." That same account confirms the genuinely compact, sporting riding position built into this bike: "the Honda GB500 is a compact motorcycle, and six-footers will find it cramped, even though the monoposto single seat measures 31in high... no passenger footpegs are fitted. The riding position is sportingly forward, with the rider's footpegs sited rearwards." Hagerty's own confirmed styling details note "a dark green metallic with gold pinstriping, a Velocette-style indented tank" as the signature launch colorway.

BikesWiki's own production history confirms this exact model's genuine international rollout: originally introduced in Japan in 1985 in both 400cc and 500cc configurations, with the US market receiving only the larger 498cc version starting in 1989-1990. Iconic Motorbike Auctions' own account confirms the genuine commercial disconnect this bike faced at launch, despite its now-legendary status: "the average American rider shopping for a Japanese bike at the time was more interested in the bigger supersport replicas, but the Tourist Trophy has become a cult classic." Braking used a single 256mm front disc and a 138mm rear drum, with a 20-litre (5.3 US gallon) fuel tank delivering genuinely strong real-world economy in the 45-60 mpg range, and dry weight settling around 157kg (346 lbs).

This factory service manual covers the procedures, torque specs, and diagrams needed to keep a 1989-1990 GB500 Tourist Trophy running the way it was built to.