It may well have come off a Maybach V-12, but if so it wasn't a 1400 cc engine. Maybach's Zeppelin line of luxury automobiles was powered by V-12s, but they started at more than 6 liters. AFIK the smallest engine Maybach ever made was between 3 and 4 liters and used in cars in the late 30s. However I don't think it was a V-12.
I don't think Maybach ever built motorcycles.
14 liters maybe.--RC
"Sometimes history doesn't repeat itself. It just yells 'can't you remember anything I've told you?' and lets fly with a club. -- John W. Cambell Jr.