Harley-Davidson started shipping the Street series to select countries in the first quarter. Image source: Harley-Davidson.

Shares of Harley-Davidson (HOG -13.65%) revved up a 6.7% gain in pre-market trading, following the release of the motorcycle maker's first-quarter results. The stock is setting new multiyear highs on the news.

Sales increased 11% year over year to $1.6 billion. Diluted generally accepted accounting principles earnings rose 22% to $1.21 per share. Analysts has been looking for earnings of $1.08 per share on about $1.5 billion in revenue.

The company reported $178 million in positive free cash flow, up from negative $131 million in the year-ago period. Harley shipped 80,682 motorcycles in the first quarter, a 7.3% year-over-year improvement.

The average selling price per bike worked out to $16,175 in the quarter, up from $15,339 in the year-ago period.

Looking ahead, management expects to ship 92,000 to 97,000 motorcycles in the second quarter, up from 84,606 units in the second quarter of 2013. Full-year guidance remained steady at roughly 8% year-over-year unit growth.

Harley-Davidson CEO Keith Wandell likes the diversity of Harley's strong sales.

"Together with our dealers, we continued to expand the appeal of our products and the Harley-Davidson experience," said Wandell in a prepared statement. "Harley-Davidson dealers sold more than four times as many new, on-road motorcycles, 601cc and up, to U.S. young adults last year, and among riders age 35-plus, more than nine times as many to women, more than six times as many to African Americans and more than seven times as many to Hispanics, as the nearest competitor."