* Q1 profit of 51 cts/shr misses 53 cts Wall St forecast
* Lowers bottom end of 2011 motorcycle shipment forecast
* Cites Japan supply chain interruptions
* Shares fall 1 pct (Rewrites first three paragraphs; Adds analyst comment, byline; Updates shares)
By Kyle Peterson
CHICAGO, April 19 (Reuters) - Harley-Davidson Inc reported a quarterly profit that fell short of Wall Street forecasts and trimmed its 2011 shipment forecast, and its shares fell 1 percent in premarket trading on Tuesday.
The motorcycle maker reported a 3.5 percent increase in quarterly sales of new motorcycles, but trimmed its full-year shipment forecast because of supply chain interruptions resulting from the earthquake and tsunami in Japan.
First-quarter earnings jumped from a year earlier, driven largely by a 150 percent rise in income from its financial services unit.
Harley-Davidson is seeing renewed demand for its motorcycles as the economy recovers from a downturn. Its shares fell 1 percent to $39.28 in premarket trading after dropping more than 5 percent earlier.
"We are pleased by the growth of our dealers' new motorcycle sales on a worldwide basis, led by strength in Europe, even as we continue to encounter some headwinds in the U.S. related to the challenging macro-economic conditions," Chief Executive Keith Wandell said in a statement.
The company said its first-quarter income was $119.3 million, or 51 cents per share, compared with income of $68.7 million, or 29 cents per share, in the year-ago period.
Analysts on average had expected the Milwaukee-based company to report a profit of 53 cents per share, according to Thomson Reuters I/B/E/S.
Harley-Davidson said its first-quarter earnings improvements were driven largely by income from its financial services, which soared 154.6 percent compared with the first quarter of 2010.
Harley-Davidson said its financial services segment earned $67.9 million in the quarter, up from $26.7 million in the year-ago quarter. The increase was due to continued improvement in credit performance, the company said.
Harley widened its full-year motorcycle shipment forecast to accommodate a slight supply chain interruption arising from the March 11 earthquake and tsunami in Japan.
The new forecast is for the company to ship 215,000 to 228,000 Harley-Davidson motorcycles to dealers and distributors in 2011. That outlook is changed from 221,000 to 228,000 motorcycles.
"We continue to assess our supply chains and as a precaution we have decided to modestly reduce the lower end of shipment guidance following the events in Japan," Wandell said.
The company said it expects to ship 62,000 to 67,000 motorcycles in the second quarter.
"We think Harley will ultimately get a pass on the Japan issue, so the stock should recover," RBC Capital Markets analyst Edward Aaron said in a research note. (Reporting by Kyle Peterson, editing by Maureen Bavdek)