- USA model

The Honda MB5 was imported for exactly 1 year here in the USA, 1982. The model designation is MB50C here in the US. The colors it came in were black body and frame and a red stripe, and red body and frame with a blue stripe. It had a 49cc, 2-stroke, air cooled engine with a counter-balancer for minimal vibration. The engine used oil injection so you didn't have to premix the gas and oil. CDI ignition, no points. 16mm Keihin carburetor with manual choke. 5-speed transmission with a manual clutch, and chain driven final drive. Speedometer and tachometer (both cable driven) were standard. 18 inch 3-spoke ComStar mag-style wheels. Dampener rod forks in front and twin 5-position adjustable shocks on a conventional swingarm in the rear. Hydraulic front disc brake and a drum in the rear. The Honda accessory luggage rack was available and is kind of a rare find today.

Starting Vin # for the Honda MB5 is:  JH2AC010*CK000011 
* is any number/letter

'82 MB5 USA model brochure


Service Manual, Wiring Diagram & Owners manual are all available on the Resource page

1982 Honda MB5 specifications (USA model)

Overall Length 74 in  (1880mm)
Overall Width 27.8 in  (705 mm)
Overall Height 40.4 in  (1025mm)
Wheelbase 47.8 in  (1215 mm)
Seat Height 29.5 in  (750 mm)
Foot Peg Height 12.2 in  (310 mm)
Ground Clearance 6.3 in  (160 mm)
Dry Weight 174 lb  (79 kg)
Curb Weight 198 lb  (90 kg)

Type Cross line backbone
Front Suspension, 
Telescopic fork (dampener rod), 
4.9 in (125 mm)
Rear Suspension,
Swingarm/twin shock absorber,
3.5 in  (90mm)
Gross Vehicle Weight Rating 416.7 lb  (189 kg)
Vehicle Capacity load 220.5 lb  (100 kg)
Tire Size, front & rear 2.50 x 18
Tire Pressure, front
25 psi (175 kPa) front
32 psi (225 kPa) rear
Front brake, lining swept area  Single disc brake, 59.6 sq in
(384 sq cm)
Rear brake, lining swept area Internal expanding shoe,
13.4 sq in  (86.4 sq cm)
Fuel Capacity 2.4 US gal  (9.0 liters)
Fuel reserve capacity 0.5 US gal  (2.0 liters)
Caster angle 25 degrees
Trail 2.8 in  (70mm)
Front Fork Oil Capacity 2.54 ozs  (75 cc)

Type Air cooled 2-stroke, reed valve
Cylinder arrangement Single cylinder 40 degree incline
Bore and Stroke 39.0 x 41.4 mm  (1.54 x 1.63 in)
Displacement 49cc  (2.98 cu in)
Compression ratio 7.6:1
Max Horsepower 7.0 BHP @ 9000 rpm
Max Torque 4.05 ft-lb (5.6 N-m)
Oil Capacity, transmission
Oil tank, for oil injection
1.1 US qt (1.0 liters)
1.2 US qt (1.1 liters)
Lubrication system Forced (engine) and wet sump (trans)
Air Filtration Oiled polyurethane foam
Cylinder compression 185 psi  (1275 kPa)
Engine weight 38.6 lb  (17.5 kg)
Idle Speed 1400 rpm

Carb Type Keihin PF 15, 16mm venturi bore
ID Number PF 15A
Air Screw initial setting 1 3/8 turns out
Float level 13.5 mm  (0.53 in)
Main jet, standard #105
Main air jet, standard #210
Jet needle & position, standard 37B - 2nd groove
Slow/Pilot jet, standard #38

Drive Train
Clutch Wet, multi-plate
Transmission 5-speed constant-mesh
Primary reduction 4.117
Final reduction (sprockets) 3.307 (43/13)
Gear ratios, 1 to 5 3.083, 1.882, 1.400, 1.130, 0.960
Gear shift pattern left foot operated, 1-N-2-3-4-5

Ignition CDI (Capacitor Discharge Ignition)
Ignition timing "F" mark 19 +or- 3 degrees BTDC @ 3000 rpm
Full retard 10 +or- 5 degrees BTDC @ 7000 rpm
Starting system Primary kickstarter
Generator AC generator 66W @ 5000 rpm
Battery capacity 12V - 2.5 AH     (YB2.5L-C)
Spark plug, standard
extended high speed riding
cold climate, below 5 C or 41 F
Spark plug gap 0.6-0.7 mm (0.024-0.028 in)
Fuse 7 Amp

Headlight (high/low beam) 31.5/30 W (sealed beam)
Tail/Stoplight 8/27W  3/32 cp  (#1157)
Front turn signal 23W  32 cp  (#1073)
Rear turn signal 23W  32 cp  (#1073)
Speedometer light 3.4W  2 cp  (#158)
Tachometer light 3.4W  2 cp  (#158)
Neutral light 3.4W  2 cp  (#158)
Turn signal indicator 3.4W  2 cp  (#158)
High beam indicator 1.7W  1 cp  (#53)

   Color Code

    Red - R33 Helios Red
    Black - NH1 Black

European model Honda MB5

Here is a good example of a stock 1980 European MB5

    The Honda MB5, more commonly know as a MB50, was produced in Europe for 3 years, 1979 to 1981. They came in black, red, and white with a blue stripe. Most all of the chassis and appearance parts are the same as the USA model. The euro model did get a fairing around the headlight with a very small windshield incorporated. Clip-on style handlebars for the euro version instead of standard bars on the US version. Spotting an MB5 is hard, and finding one with the original fairing, is nearly impossible.

    The motors are where the differences start. All of some of the 1979 models had a 4-speed transmission, or gearbox as some call it. Later models had a 5-speed like the US version. The 4-speed gearbox was mainly used in the Netherlands throughout the MB5's entire production. Most of them are modified to 5-speed gearboxes, as this improves acceleration.  The UK, Belgium, Germany and Spain got 5-speed gearboxes from the end of 1979.
    The MB5 was never officially imported in France, but a few hundred were imported by privateers that bought one in another country. It never was a big hit there, as the French preferred French mopeds over Japanese ones.
    In Europe, a 50cc bike is considered a moped, and is restricted to a designed top speed of 30 MPH, or about 48 km/h. This is done by restricting the diameter of the first part of the exhaust, and another restrictor is placed between the airbox and the carburetor.  It is highly illegal to remove those restrictions.  The bike can be impounded by the police if it is capable of reaching speeds above 30 MPH.  Needless to say, 85% of the mopeds in Europe are de-restricted or tuned. Fines are about $1,500 if you get caught driving a de-restricted or tuned example. A Keihin HM 16-6 carb, which is a 13mm diameter, with a #62 main jet, the restricted engine will choke with the #75 or #80 jet that is commonly used in the de-restricted versions. The idle speed is 1200 RPM, but the de-restricted versions will stall if it isn't raised to 1400 RPM. No numbers on BHP or torque are given in the UK specs, but to comply with the 30 MPH regulation that is enforced in Europe, it is likely that it produces around 2,5 BHP at 5500 RPM.  The redline is at 6000 RPM, as the engine can't turn higher revs with the restrictors in place. Removing the restrictions results in an output of around 7 BHP at 9000RPM, like the US version. Fuel economy in the restricted version is the same as US version would be if you drove around without exceeding 6000 RPM.

Here are some specs on the UK-spec MB5                        Below is the USA version

length : 1915 mm / 75.39 in                                                1880 mm / 74 in
width : 665 mm / 26.18 in                                                    705 mm / 27.8 in
height : 1160 mm / 45.67 in                                                 1025 mm / 40.4 in
wheelbase : 1220 mm / 48.03 in                                          1215 mm / 47.8 in
seat height : 750 mm / 29.53 in                                            same
ground clearance : 160 mm / 6.30 in                                    same
weight (dry) : 83,5 Kg / 183.7 lbs                                       79 kg / 174 lbs
weight (ready to run) : 93,0 Kg / 204 lbs                             90 kg / 198 lbs

The differences in size can be explained a bit.  The European MB is less
wide because of the clipon-style handlebars, and is higher because of the
fairing. The extra weight is a result of the fairing.