(Adds forecast, share move)

April 18 (Reuters) - U.S. motorcycle maker Harley-Davidson Inc HOG.N kept its 2017 outlook unchanged despite its first-quarter shipments hitting the high end of its forecast.

The Milwaukee-based company's shares were down 5.5 percent at $56.15 in premarket trading on Tuesday.

The company, which commands about half the U.S. big-bike market, said motorcycle shipments fell 14.7 percent to 70,831 units in the first quarter ended March 26, compared with its previous forecast of 66,000-71,000 units.

Harley said it continues to expect full-year shipments to be flat to down modestly.

Harley's shipments have been hurt amid rising competition as rivals such as Japan's Honda Motor Co Ltd 7267.T and Polaris Industries Inc PII.N , which makes Indian motorcycles, cut prices to lure buyers forcing the company to offer dealer rare rebates on its 2016 motorcycles as an incentive to clear older inventories.>

Revenue per motorcycle fell about $342 to $$15,526 in the first quarter, Harley said.

The company's net income fell to $186.37 million, $1.05 per share, in the quarter, from $250.49 million, or $1.36 per share, a year earlier.

Revenue from motorcycles and related products fell 15.7 percent to $1.33 billion.

(Reporting by Rachit Vats in Bengaluru; Editing by Maju Samuel) ((Rachit.Vats@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 80 6749 3798; Reuters Messaging: rachit.vats.thomsonreuters.com@reuters.net))