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.
1928 Excelsior Big Bertha Hill Climber