The Suzuki M31 was a sibling to the M30, launched in June 1963 as the successors to the Selpet MA/ME models. The M30 and M31 looked very similar, the shape of the rear mirror being the only plainly visible difference between the models.
The design
of the M31 with its underbone frame and leg shield was not very original or innovative, all the larger motorcycle manufactures in Japan started to produce similar models after Honda launched its Super Cub in 1958. It had such an influence that it caused virtually all mopeds made by other manufacturers to be shaped like the Cub.
It was called a ”step through” model, meaning that its frame didn't have a top tube. The the fuel tank was placed under the seat and the engine was mounted as low as possible, making it easy to get on and off the bike without lifting your leg high.
The M31 was also called Suzuki Selpet 55, telling that the bike had a 55cc engine. The M30 had a slightly less powerful engine with a 50cc engine displacement. That model was even called Selpet 50, or Suzuki M30 Mokick.
The word ”mokick” was used in some countries meaning ”moped with a kick starter” because you started it by kicking like a proper motorcycle, as opposed to pedaling, like a moped.
The 55cc 2-stroke motor produced 4.5 horsepower paired with a 3-speed transmission and a automatic clutch. In English speaking countries the M31 was marketed as Suzuki 55 Suzy (M31).
It used a new mechanism, an automatic centrifugal clutch, which allows to change gears without disengaging the clutch. It is mounted on the countershaft, and is trouble-free and requires no adjustment. In addition, a Neidhardt (special rubber) shock absorber mechanism is built into the centrifugal clutch, which smoothly absorbs shocks when starting or changing gears.
The Selmix/CCI separate lubrication technology that Suzuki developed in GP races to improve the reliability of 2-stroke engines, was not available for production motorcycles in 1963. The first mass produced Suzuki that used the automated lubrication method was the 250cc sports model T20 in 1965.
The M30 and M31 models still used the characteristic flat-bottomed ”horse shoe” headlight. The domestic model was sold with a single seat and a luggage rack as standard equipment, a dual seat was optional, usually a customer bought a pop-on rear seat that made mthe bike more versatile.
There was not very much difference in performance
between the 50cc M30 and the 55cc M31. The specified top speed was 70 km/h for the M30 and 72 km/h for the M31. All the other spefifications were the same, except for the displacement and the maximum power and torque that the engines could provide. The specified peak power for the M30 was 4.0 hp, 0.5 hp less that its sibling. The M30 also developed slightly less torque (0.45 kg-m) than the M31 (5.0 kg-m), both at 5,000 rpm.
A service manual I managed to find revealed that the colors used on Suzuki 55 Model M 31 were as follows: Light Blue (002), Black (019), Permanent Red (061), Pure White (064) and Light Permanent Blue (075).
 |
