In remarkable original condition! The "M" cylinders, developed by
the legendary Arthur Lemon, could be tuned for more power without
over-heating. A pair of "M" cylinders on the Super X crankcase gave
the 61 cubic inch V twin a major horsepower boost. This
modification was nicknamed "Big Bertha". Extremely rare because
very few of these factory-built racers were ever produced. William
V. Altman was part of the Joe Petrali team who won more than 31
consecutive hill climb competitions in 1928 and 1929.