As found on the Internet, by F-Head
1903 HARLEY RESTORATION :
Intrigue Builds Around Original Bike

Few veteran manufacturers know the where abouts of their original product. One of the intriguing aspects of Harley-Davidson ís recent restoration of the first bike the company ever built in 1903.
Another wrinkle is the mystery surrounding the story behind the first bike ever produced by William Harley and the three Davidson brothers.
We know where our first bike is, says Harley-Davidson Historian Martin Rosenblum. Its story is a real mystery, though. We've been working day and night to find the true story behind serial number 1.The original Harley-Davidson was diligently restored to its 1903 configuration by Motor Company Archives employee Ray Schlee with assistance from John Rank, a Milwaukee car and truck dealer who restores motorcycles as an interest.Those who attend the 95th Anniversary celebration next year can see the bike, which was recently displayed at Bike Week in Daytona.Rosenblum and Schlee are certain they have the first production Harley -- a single-cylinder engine with 26.84 cubic inches of displacement that makes 3*hp. Evidence suggests it was a prototype made for racing. Harley-Davidson built two additional 1903 models for sale, but there is no trace of either one.
According to one possibility, the first bike was sold to a Mr. Mayor of Chicago in 1904 and changed hands three times before Steve Sparough, an automotive repairman from Chicago, bought it.
I make trips with my machine to repair cars if they get into trouble out in the country, Sparough wrote to a Harley-Davidson distributor, C.H. Lang, on April 15, 1912.
Sparough may have sold the motorcycle back to Harley-Davidson between 1912 and 1915.
Another possibility was recently discovered when studying Milwaukee County Historical Society photos that are part of the original Archive collection.
The first Harley may have been put into storage at the company, then dusted off in 1915 to be displayed at the Pan-American Exposition motorcycle show in California.