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Honda MB50

This is what Motor Cycle Mechanics (May 1980) had to say about the "new" Honda MB5. Tasty MB50......

The new honda MB50 looks good, sounds good and smells good - in fact, it's pretty tasty! With its limited 30mph performance any six teener special will have to appeal to the senses if it is going to sell; and the MB50 does.

Looking more like a road racer than a 30mph "slowped", the little Honda shouts performance from ever viewpoint. the clip-on type bars , the small flyscreen and the cast alloy wheels all suggest this bike can move, what a pity it's all a sham.

Don't get the wrong idea, riding the MB50 in London traffic is just as exciting as riding any other 30mph restricted machine - in place of "exciting" you could read dangerous!

 There simply isn't enough power to keep up with the majority of the traffic which flows nearer to 40mph than 30. Honda have certainly done a good job while working within the limitations of 30mph restriction law. You do get an impression of speed, but that's all you get.

If the Honda express can manage its 30mph performance with only one gear how come the MB50 needs five? It's all part of honda's deception. First gear is very low. In fact, flat out are going little faster than walking pace _ but the take off is teriffic. Even with a modest amount of throttle you can lift the front wheel by dropping the clutch although it's not recommended to help transmission life! The tacho doesn't exactly whizz around the dial but you can use it to change up at peak revs.

Once you reach third gear, I found it just as quick to prod the pedal straight into top, rather than wring the motor out in fourth. Top speed indicated indicated was 35mph which is about right allowing for speedo error and the govenment's percentage leeway.

honda make a point of stressing the MB50's low centre of gravity and three-spoke Comstar wheels. we can't say how much this contributes to the handling but we can say that the bike handles quite well _ for a moped.

The disc brake is certainly more than a match for the performance and it is pretty easy to lose more speed than you intended because of it's deceptive power and light action. The chassis could cope with a lot more performance but Honda claim it isn't posible to tune the engine.

Basically, the power unit is a single cylinder two-stroke with reed valves controlling the intake. The inlet port has a similar bore to the fuel tap on the CB900F and an equally restrictive exhaust port. What is interesting is that Honda have seen fit to design the motor with a "balancer" shaft.

It's difficult to believe any two-stroke this small needs such a device to damp out vibrations and it may just be a way of increacing the flywheel mass without building a large crankcase to house it. the motor also features electronic ignition with its own built-in advance system.

The combustion chamber is a new design and this, Honda claim, allows the engine to run at low town, speeds without fouling the plug. The massive finning on the engine is also said to aid low-speed cooling. Since the engine produces just about zero power, and therefore heat, we would think that the cooling fin size is designed for looks rather than efficency.

As for the low speed, clean running, combustion chamber I can't see anyone riding this bike at anything other than at flat-out pace! 

In the UK the MB5 was available in three colours. Black was the most popular chioce, followed by red. White was a poor selling colour and as a result it is now a rare bike. In mainland Europe blue was also offered.

Engine Data: (Restricted UK Specification)

  • Type: Air Cooled, Single Cylinder, 2 Stroke
  • Bore & Stoke: 39mm x 41.4mm
  • Displacement: 49cc
  • Compression Ratio: 6.4:1
  • Lubrication System: Honda 2 stroke oil injection system
  • Oil capacity:
  • Transmission 1.76 pints
  • Engine 1.94 pints
  • Starting System: Primary Kick
  • Maximum horsepower: 2.55 PS / 6000 rpm (DIN)
  • Maximum Torque: 0.41 kg-m / 4500

Frame:

  • Type: Cross Line Backbone Design
  • Front Suspension: Telescopic (travel 4.9inch)
  • Rear Suspension: Swing Arm 3.5 inch
  • Front Tyre: 2.50 x 18 - 4PR
  • Rear Tyre 2.50 x 18 - 6PR
  • Front Brake: Disc
  • Rear Brake: Internal Expanding Shoe
  • Trail Lengh: 2.8 inch
  • Caster Angle: 65 Degrees

Transmission:

  • Type: 5-speed Constant mesh
  • Clutch: Wet multi-plate
  • Primary reduction: 4.117
  • Gear Ratios 1st: 3.083
  • 2nd: 1.882
  • 3rd: 1.400
  • 4th: 1.130
  • 5th: 0.960
  • Final reduction: 3.750
  • Drive Sprocket: 12T
  • Driven Sprocket 45T

Electrical System:

  • Ignition: Fully Transistorised
  • Alternator: 0.049kw/5000rpm
  • Battery Capacity: 6V-4AH
  • Headlight low/high: 25/25 watt
  • Tail/Stoplight: 5/21 watt
  • Indicator Light: 18watt

Dimensions:

  • Overall length: 74.0in
  • Overall Width: 25.8in
  • Overall Height: 45.7in
  • Wheelbase: 48.2in
  • Seat Height: 29.5in
  • Ground clearance: 6.3in
  • Fuel capacity inc. reserve: 2.42 imp gals
  • Dry Weight: 179lb
  • Curb Weight: 198lb

Colours Available:

  • Red, White or Black