OOPS
Known as the "Ossa Mayor" ("The big Bear"), this bike is one of the most charismatic in the history of Spanish motorcycles, and masterpiece from the engineer Fernando Batlló.
Starting from the base of a Yankee engine, to which he added two extra cylinders, one either side, making it to a 977 cc. four cylinders. Driven by his sons, Jesus
and Javier, the bike showed great potential, after electrical problems were solved first and traction (transmission of power to the ground) afterwards.
The frame was inspired on the Yankee one due to the
almost 100HP delivered."
Personal note: I have read that with cylinders from a Phantom and special exhausts the bike delivered 115 HP.