Honda C90 / Super Cub 90 (1966 to 2002)

The C90 is the 90cc member of Honda's step-through Super Cub family, the machine that put a generation of commuters, postmen, district nurses and students on two wheels. Honda's own history records that the overhead camshaft engine first seen in the C65 was spread across the 50cc and 90cc models in 1966, creating the second generation of Super Cubs, and the C90 stayed in production in one form or another until 2002.

The recipe never changed much: a horizontal single-cylinder four-stroke slung under a pressed and tubular steel spine, a three-speed gearbox with an automatic centrifugal clutch, leading-link forks, enclosed chain, drum brakes and plastic legshields. It is slow (period owners and modern guides agree on a realistic cruising limit of around 50 to 55 mph) but famously frugal and tolerant of neglect.

For buyers, the C90's strength is also its weakness. Huge numbers were made and worked hard, so many "restored" examples are former commuters with a quick coat of paint over a tired frame. A 1973 machine sits in the early, six-volt, points-ignition era, before the 1980s updates that brought 12-volt electrics and CDI. Originality of small parts, frame condition around the rear mudguard, and evidence of regular oil changes matter far more than shine.

• Years: OHC C90 from 1966 (Honda dates the OHC engine's adoption across the 50 and 90 to 1966; MCN's buying guide dates the UK C90 from September 1967) until 2002.
• Engine: air-cooled, horizontal single-cylinder four-stroke with a single overhead camshaft and two valves; 89cc on early bikes, reduced to 86cc from 1983 according to MCN.
• Power: MCN quotes 8bhp; figures vary between sources and by year.
• Gearbox: three-speed with a centrifugal clutch, operated by a heel-and-toe pedal; no hand clutch lever.
• Electrics: 6-volt with contact-breaker ignition on early bikes; 12-volt and CDI ignition from the 1983/84 C90-C onwards.
• Chassis: steel backbone frame with pressed-steel rear section that also forms the rear mudguard; leading-link front fork; twin rear shocks; 17in wheels; single leading shoe drums front and rear.
• Production: part of a Super Cub family whose cumulative output Honda announced had reached 100 million units in October 2017.

• Early C90 (to 1977): 89cc, 6-volt electrics, points ignition. A 1973 bike belongs here.
• C90Z-2 (1977 to 1979): revised carburettor and a handlebar choke lever (MCN).
• C90Z-Z (1979 to 1983): gearchange pattern altered (MCN). Sources describe the shift patterns differently; Classic Bike Hub says the 90 changes all down while the 50 and 70 go one up, two down, so check the pedal action against the period handbook rather than assuming.
• C90-C (1983 to 1984): 86cc engine, CDI ignition, 12-volt electrics, new headlamp.
• C90-E onwards (1984 to 2002): rotary gear selector, fuel gauge, later wheel and brake plate changes; electric start C90M variants from 1985.
• A Honda history page notes that an independent position light appeared on the top-of-range 90 before the 1969 C50 update, a small detail that can help with period correctness.
• Related but different: the C50 and C70 use a different engine and, until the early 1980s, slightly different chassis parts, so not every Cub part swaps across.

Frame and bodywork

• The rear mudguard is part of the frame on these bikes. Classic Bike Hub calls rust here the single most important check: severe corrosion can let the shock mounts pull out or the frame break. Look underneath and inside the mudguard with a torch.
• MCN also flags the frame down tubes above the engine, and the insides of the fork and swinging arm.
• Fresh paint or underseal over the rear frame deserves suspicion. Ask permission before probing, but look closely for filler and ripples.
• Legshields are brittle and often cracked; seats split; indicator lenses crack. These are easy to replace but affect originality.
• Check the chaincase: lower halves are often missing and the locating tongues get bent.

Engine

• Ask for a cold start if the auction allows it. The engine should not smoke heavily or rattle. A cam chain rattle can be adjusted, but Classic Bike Hub treats it as a sign of poor maintenance.
• Oil changes are the key to longevity because the sump capacity is small; guides suggest roughly every 1,000 miles. Look for oil leaks around the breather and gaskets.
• Check whether the engine is original. MCN warns that some bikes carry Chinese pit-bike engines; these change the character and lose originality. Compare the engine number with the V5C.
• Carburettor fixings can work loose and leak fuel, and choke cables can stick (owner reports).

Gearbox, clutch and drive

• The centrifugal clutch slips if adjustment is wrong. With the engine running, gear engagement should be positive without a big lurch.
• Owner reports note that a dry or rusty chain inside the enclosed case makes the gearchange worse. If a rubber inspection bung is fitted, look at the chain.

Suspension, wheels and brakes

• Leading-link front forks rise under braking and the bushes wear; squeaks and a bouncy feel point to worn fork and shock bushes. Rock the front end and listen.
• Front suspension can seize on neglected bikes.
• Spokes corrode, so check each one for rust and looseness.
• The front drum is weak by modern standards; check the brake operating arms for travel and the cables for fraying.

Electrics

• On a 6-volt bike, expect modest lighting. Check every lamp and the horn work, and look at the battery: owners often forget to top it up.
• Look for added wiring, non-standard switches or a 12-volt conversion if originality matters to you.

Identity and paperwork

• Locate the frame number on the frame and the engine number on the crankcase and check both against the V5C.
• A 1973 bike should be 6-volt with points ignition. A 12-volt CDI engine indicates a later engine has been fitted.
• Ask for MOT history and any receipts; commuting mileage can be very high.

Parts supply is generally strong. MCN notes that spares for 1980s-onward models are easy to find, while many parts for 1960s and 1970s bikes are budget pattern items whose quality varies. Classic Bike Hub stresses that spares for the step-throughs are widely available. Keep original badges, lenses and switchgear if you have them, because correct early parts are harder to find than mechanical consumables.

Clubs:

• Honda Owners Club (GB): https://www.hoc.org.uk/ (opens in a new tab) (mainly social, with branches across the UK).
• Vintage Japanese Motorcycle Club (VJMC): the UK club for Japanese machines over 15 years old, listed by Footman James at https://www.vjmc.com/ (opens in a new tab). We could not open the VJMC site directly during research.

• Has the rear frame and mudguard section been repaired, and if so by whom and with what? Are there photos from the restoration?
• Is the engine the original unit, and does its number match the V5C?
• When was the oil last changed, and is there any record of regular servicing?
• Has the bike been converted to 12-volt or fitted with non-original electrics or a different engine?
• Which parts on the bike are original Honda and which are pattern replacements?