Bultaco. Model Speedway. 250cc.

The Flat track, flat-Track in English) is a discipline of sport rider speed on a circuit (or "track") of earth, very popular in the USA where it is originating. It is similar to the Speedway european although the races are run at a higher speed and have enough quirks. It is also known as a Dirt Track (the Track of debris, or better: a Track of land).
The majority of racing Flat Track is run on oval tracks of land. The tracks may have a length of one mile, half mile, or shorter. Those that make less than 3/8 parts of a mile are considered short-track or Short Track.
Usually the races are run in the opposite direction to the needles of the clock, although some races, known as TTS, are done on tracks with curves of left and right. These often contain a jump as a minimum.
The main competition in the USA is the Grand National Championship, which consists of all the track types described above, and is organized by the AMA (American Motorcyclist Association).
Motorcycles Flat Track have more powerful engines than the Speedway, and on the contrary they have suspensions.

It is one of the machines that are prepararón to race in Palma de Mallorca, equipped with a motor Pursang MK-5. In the early 70's I think a circuit and enough fans around to this mode,the engine was a known motorcyclist of the island called Nicolas. I have conducted research to locate any of this bikes, but have practically disappeared, or by circumstances you can't access the one that I think is still preserved.

The Harley Davidson XR-750 has been the bike more common among pilots for many years, but lately abound, BMW, Aprilia, Kawasaki and Suzuki.
In the 70s they were very popular motorcycles Catalan OSSA and Bultaco, this with the model Astro, so named as a tribute to the victories achieved in the circuit Astrodome of Houston.
In the 30's played some race called Dirt Track (which in reality were of Speedway) at the Stadium of Montjuïc, but with the Spanish civil War were left to dispute. Already in the late 70's and early 80's the magazine barcelona Solo Moto organized several racing authentic Dirt Track in Barcelona, near the Diagonal, with motorcycles Bultaco Astro piloted by riders of motocross as Toni Elías, Fernando Muñoz, toni Arcarons and others.
In the 90's, taking advantage of the Great Prize of Catalunya motogp organized racing Dirt Track on a track of 1/4 mile existing along the Circuit of Montmeló, and involved american pilots speed as Eddie Lawson, Randy Mamola or Jimmy Filice, as is usual in the U.S. had begun his career running tracks Flat Track.