Harley-Davidson shares revved to their highest price in more than four years after a successful effort to attract more women riders helped produce a 20 percent increase in first-quarter revenue.

The company, which said profits in the period soared 44 percent, raised its annual profits forecast — which sent shares up 6.2 percent to $53.49.

“Women aren’t just riding on the back anymore — they’ve discovered the spirit of the open road and want something of their own,” said Mark-Hans Richer, Harley’s marketing maven.

The company specifically targeted women and other “outreach” customers — such as Hispanics and folks under the age of 34 — in the quarter.

Harley is luring females with differently designed heavyweight bikes, such as low-slung machines for shorter legs and special seats, handle bars and foot gearshifts, said Richer.

Two-thirds of women who bought big bikes in the US last year picked Harleys, the company said. They cost anywhere from $8,000 to $30,000 for custom bikes featuring white lacquer with pink flames.

Harley sales to women jumped 9 percent in the quarter compared to last year, the largest increase in several years, industry sources said.

Overall Harley revenue surged to $1.27 billion.

“Women are getting much more involved than ever before,” said Pat Murphy, vice president of research at the Motorcycle Industry Council.