In 1956 Suzuki had introduced its first twin-cylinder motorcycle with 250 ccm and an American style design, the sports model Colleda TT. So it became the predecessor of all Suzuki 250cc 2-stroke twins, including the T20, T250 and GT250. The Colleda TT featured a pressed steel frame, leading-link forks (similar to BMW), a rear swing arm with 2 absorbers and drum brakes. The final transmission is right-handed with a fully covered chain. Headlight with large covers, streamlined turn signal bodies, chrome plated turn signal holders extending backwards on both sides of the seat had fin shapes, etc. provided an image of luxurious American vehicles. Dual separated seats and a large grip in front of a passenger seat gave a modern appeal. In 1957 this engine and design was used in the low price model Colleda TP (30000 Yen less) and the business model Colleda TM in 1958.
The COX II was the last four-stroke motorcycle and most likely unchanged from the 1955 version. The only difference one can spot on the pictures, in lack of technical info, is that the center stand seems to made out of thinner material and a mudflap was attached to the front mudguard. The kick starter was placed on the left side of the engine on the four-stroke CO and COX models. The exhaust pipe ending is also different, shaped like is fish tail.
As the four-stroke machines at the time were not as reliable as the simpler two-stroke machines soon Suzuki discontinued them. All the forces were concentrated in developing two-stroke engines.
A new version of the Colleda ST was launched with a modernized engine, now delivering 7 hp. Even the 100cc Porter Free had a more powerful engine in 1956. The Colleda ST-II received a same sort of fuel tank than the COX, making to models look even more like each other. It had saddle type single seat and was equipped with a large carrier on the rear fender. Apart for the differences listed above, the Colleda COX-2 and Colleda ST-II looked a lot like each other.