Sunday, May 31, 2009

1964 Tohatsu 50cc Racing Twin

50cc race bikes aren't all that uncommon- but 50cc twins are. Tohatsu's was the first 50cc twin in road racing, as far as I can tell.

Here's a good photo that shows the tiny twin cylinders and carbs with remote float. This engine, according to H. Marc Lewis' web site, produced over 11HP at 13,000RPM:

Bridgestone followed Tohatsu's lead in 1965 with their liquid-cooled EJR-01. Tohatsu went bankrupt in February of 1964, and the entire Tohatsu racing development team moved to Bridgestone, where this bike reportedly became the basis for the 1966 liquid-cooled Bridgestone EJR-2. Honda followed in 1966 with the twin cylinder RC-116, producing 16HP at 21,500RPM, and a redline of 22,500RPM!

Then the tide seemed to turn against 50cc twins, and what 50cc road racing bikes remain today are singles. The only twin cylinder 50cc engines I know of today are designed for giant-scale model airplanes. But you never know; maybe someone will decide to put one in a motorcycle.

1 comment:

twofoot said...

Shows an interesting 50cc twin. almost 5hp for the stock unit, and I'll bet the CDI could be tweaked for more.