The Yankee Byra 1000 in full road race trim. Photo: Moto Classica

BIKES YOU’VE NEVER SEEN BEFORE: YANKEE BYRA Z 1000

Ossa was first founded in 1924 by industrialist Manuel Giro. The name OSSA is an acronym of Orpheo Sincronic Sociedad Anonima. Ossa’s famous four-leaf clover emblem isn’t actually a four-leaf clover; it is the escapement mechanism of a film projector, which is what Manuel Giro made his fortune from. Before WWII, Ossa founder Manuel Giro was the Spanish sidecar champion, along with his co-pilot Francisco Bulto (who would later found Bultaco). After World War II, with improved two-stroke engine technology obtained by the Allies from DKW as war reparation from Germany, Ossa began producing two-stroke motorcycles. Its first mass-produced model was introduced in 1949.

The arrival of Japanese technology in the mid-70s hurt the sales of European bikes, but worse yet, Spain was beset by labor strikes in the 1980s, and Ossa was forced into a labor cooperative. When that failed, the company entered into an ill-fated joint venture with Bultaco. In 1985, Ossa’s factory was shuttered, but 15 years later an investment group purchased the Ossa trademark and began producing Ossa trials and enduro models again. In a game of musical chairs, Ossa was merged with Gas Gas in 2014, but then Gas Gas was absorbed by the Torrot Group in 2015 (Ossa was not part of the deal and closed down again). When the music stopped, Gas Gas was bought by KTM in late 2019, and now Ossa is looking for new life.

The street legal version of the Yankee Byra Z 1000.

One Ossa model that most people have never seen is the Yankee Byra Z 1000. The Byra Z 1000 was a prototype road race bike that was built from the  street-legal version built alongside it. It was powered by a 997cc, four-cylinder, air-cooled, two-stroke beast that was based on two Yankee Z500 twin-cylinder engines placed side-by-side. It was engineered by Fernando Batllo and built in Barcelona. The frame was an American-made Yankee Z500 chassis, which thankfully for the 1000c four version was plenty sturdy.The John Taylor designed Yankee Z500 with a twin-cylinder 488cc two-stroke engine was sold in 1971-;72. The Byra would graft two Yankee engines together to get 1000cc.

The Yankee Z500 was the brainchild of Ossa and Bultaco American importer John Taylor. John Taylor had Ossa modify a twin-cylinder 460cc Ossa road race engine, designed by Eduardo Giro, into a 488cc dirt bike engine by mating two 250cc Ossa Pioneer top-ends, including the pistons, cylinders and heads, onto a unified two-cylinder engine case. The engine had a bore and stroke of 72mm by 60mm with two 24mm IRZ 4G dual-needle carbs. The result was an engine that could be used as a twin or a twingle. It was, to John Taylor’s mind, going to be the ultimate off-road machine. Production of the Yankee Z500 only lasted for the 1971-1972 selling seasons. Only 764 Z500s were ever built.

The two outside cylinders stuck out beyond the the gas tank of the Yankee Byra 1000.

Byra designer Fernando Batllo started with two Yankee Z500 frames and then turned the twin-cylinder Ossa engine into a four-cylinder engine. It’s width eliminated it as a dirt bike, but Batllo felt that it could be a successful road race machine. The prototype bike was race successfully at the 24 hours of Montjuich races in 1972 and 1973.

The ill-fated Yankee Byra Z1000 at the 1974 Montjuich 24 Hour race.

Unfortunately, at the 1974 Montjuich event, the Byra crashed into a tree at turn three (at Font del Gat) killing the rider and bringing an end to the racing history of the Byra Z1000. The street-legal Ossa/Yankee/Byra Z1000 is on a permanent display at the Bassella Motorcycle Museum in northern Spain.