Honda NA50 Express II 1977-1981 Service Manual

Rider Magazine's own retrospective quotes Honda's own genuine marketing philosophy behind this sibling's redesigned, more approachable proportions: "the marketing fellows thought that a new look would be in order to appeal to the new buyer... make the Express look harmless, non-intimidating. And light of weight, so it could be pushed around like a bicycle. Make it so easy to operate that it would appeal to the person whose sole experience on two wheels had been a single-speed bicycle. To enhance the bicycle motif, the designers did away with any minor bodywork, leaving a frame, a discreetly hidden engine and two wheels. And they did not want to burden this new buyer with pedals—they wanted a noped—no pedals."

Power comes from the same fundamental 49cc air-cooled two-stroke single-cylinder engine shared with the standard NC50 Express, with a 6.5:1 compression ratio, delivering a claimed 4.5 hp measured on the dyno at 7,000 rpm — Rider Magazine's own detailed technical account confirms the genuinely clever oil-delivery system built into this engine: "this was not a conventional two-stroke, mixing oil and gas in the 12mm carburetor and passing the fuel through a reed-valve, lubricating all the moving parts with the mixture. Instead, Honda utilized a separate oiling system, employing a crankshaft-driven plunger pump which used engine speed and load to inject the right amount of oil into the manifold, not the carb, to make sure the moving bits and pieces in the engine were properly lubricated."

Moped Army's own detailed year-by-year account confirms exactly what genuinely distinguished the Express II from the standard Express model it launched alongside: "the Express II (NA50) is introduced alongside the Express. Both feature the same drivetrain, but the new model is built with a redesigned frame and larger seat" — Specs Motorcycles' own account confirms further detail differences: "a different frame, 'more comfortable' seat, tree handle bars, and a slightly larger gas tank." Moped Army's own account confirms genuine incremental refinement continued through the model's short life: "1980 Turn signals and a larger battery to match are added."

The genuinely significant mechanical update within this exact range arrived in the model's final production year — Wikipedia's own account confirms "for the NA50's final year of production in 1981, it received the same upgrades as the NC50 (CDI, auto choke, kick start) as well as a 2-speed automatic transmission," a real drivetrain upgrade over the standard single-speed transmission used on both the NA50 and NC50 through 1980. WebBikeWorld's own confirmed 1979-model specification sheet documents exactly what an earlier, pre-upgrade example runs: "wind-up spring starting system, points ignition, and manual choke" — a genuinely important distinction from the improved 1981 configuration, since these two model years within the same nameplate run meaningfully different ignition, starting, and transmission hardware. Monster Scooter Parts' own confirmed production dates place the NA50's full run at "1979-1981," closing out with the model discontinued in favor of the Urban Express (NU50) that replaced it for 1982, sharing a similar frame but running the more sophisticated belt-driven, variated transmission borrowed from the Express SR (NX50) introduced that same 1981 model year.

This factory service manual covers the procedures, torque specs, and diagrams needed to keep a 1979-1981 NA50 Express II's two-stroke engine and driveline running the way it was built to.