Harley - Davidson WLA The WLA is a model of Harley - Davidson motorcycle that was produced to US Army specifications in the years during and around World War II . It was based on an existing civilian model , the WL , and is of the 45 solo type , so called due to its engine and single - rider design . The same engine , in a slightly lower state of tune , also powered the three - wheeled Servi - Car ( the " G " family ) , leading to the " solo " distinction . Model designation . The model number breaks down as follows : History . Harley - Davidson began producing the WLA in small numbers in 1940 , as part of a general military expansion . The later entry of the United States into World War II saw significantly increased production , with over 90 , 000 being produced during the war ( along with spare parts the equivalent of many more ) . Harley Davidson would also produce a close WLA variant for the Canadian Army called the WLC and would also supply smaller numbers to the UK , South Africa , and other allies , as well as filling orders for different models from the Navy and Marine Corps . Unusually , all the WLAs produced after Pearl Harbor , regardless of the actual year , would be given serial numbers indicating 1942 production . Thus , war - time machines would come to be known as 42WLAs . This may have been in recognition of the use of the continued use of the same specification . Most WLCs were produced in 1943 , and are marked 43WLC . The precise serial number , as well as casting marks , can be used to date a specific motor accurately , and some other parts bear year and month stamps . Frames and many other parts were not tagged with the serial number , and cannot generally be dated . ( This is common prior to adoption of the VIN . ) Many WLAs would be shipped to allies under the Lend - Lease program . The largest recipient was the Soviet Union , which was sold over 30 , 000 WLAs . Production of the WLA would cease after the war , but would be revived for the Korean War during the years 1949 – 1952 . Most WLAs in western hands after the war would be sold as surplus and " civilianized " ; the many motorcycles available at very low cost would lead to the rise of the chopper and other modified motorcycle styles , as well as the surrounding biker culture . Many a young soldier would come home hoping to get a Harley - Davidson like he saw or rode in the service , leading to the post - war popularity of both the motorcycle and the company in general . However , this also ensured that few nearly - original WLAs would survive in the US or even Western Europe . A significant number of WLAs were left in the Soviet Union , and either stored or put in private hands . With little access to parts and no chopper culture , and no export path to the West , many of those WLAs were preserved during the Cold War . Russia and other former Soviet countries are now a major source of WLAs and parts . Military changes . The WLA is very similar to civilian models , specifically the WL . Among the changes making it a military model : Uses . The US Army would use motorcycles for police and escort work , courier duties , and some scouting , as well as limited use to transport radio and radio suppression equipment . Allied motorcycles were almost never used as combat vehicles or for troop mobility , and so were rarely equipped with sidecars as was common on the German side . Nevertheless , the WLA acquired the nickname " Liberator " , since it was seen ridden by soldiers liberating occupied Europe . Technology . The engine of the WLA is a side - valve design , which is reliable though not particularly efficient in comparison to overhead - valve designs . Harley Davidson already had overhead valve engines in production for its Big Twin lines , but the " small twin " flathead design was popular in applications needing reliability more than power . This engine remained in production from 1937 to 1973 in the Servi - Car , although it was superseded in two - wheeled motorcycles by the more advanced flathead engine used in the Model K ( the ancestor of the OHV Sportster ) in 1952 . Though the model designation suggested high compression , for reliability , the Army version actually used a medium - compression version . In modern terms , the WLA ' s compression ratio of 5 : 1 is very low . Due to this low compression , a WLA will run on 74 octane gasoline , necessary due to the poor quality of refining at the time , although fuel technology would improve rapidly during the war . The WLA also features springer front suspension . Harley - Davidson would not adopt telescopic front forks until after the war . The rear wheel had no suspension , giving this type of motorcycle the nickname " hard tail " . Other military motorcycles . Harley - Davidson provided motorcycles to the Army during World War I and for earlier excursions against Mexican bandits like Pancho Villa . During World War II , the Army produced a specification for a motorcycle much like the BMWs used by German forces . That meant shaft drive , a boxer engine , and several other features that made the BMWs exceptionally reliable and low - maintenance machines . Harley - Davidson produced the XA based closely on the BMW . Though an excellent machine , only about 1 , 000 were produced . Due to its new features and low production , the XA was expensive , and by that time it was clear that the Jeep was the Army ' s general purpose vehicle of choice ; the less advanced but cheaper WLA was considered sufficient for its limited roles . Other motorcycles produced by HD for World War II included US Army and Canadian versions of the Big Twin EL family , the ELA and ELC , as well as an Army version of the UL , the ULA . These were produced mainly for " home front " use , and not in very large numbers . Consequently , they are very rare today . Indian , Harley - Davidson ' s major competitor at the time , also produced a war - time model , the Indian 741 , and a longitudinal V - twin shaft - drive model , the Indian 841 . Harley - Davidson would later produce the MT350E , after acquiring the British Armstrong company in 1987 . These were dual - sport machines , capable of both on - road and off - road service , powered by 350 cc Rotax engines . The MT350E was a redesign of the 500 cc Armstrong MT500 , which reduced weight , added an electric start , and upgraded pollution standards . The MT500 began as the Italian SWM XN Tornado , which Armstrong acquired the rights to in 1984 when SWM liquidated , and then modified for military use with assistance from CCM . The MT350E mostly saw British and Canadian service , and some are still in use .