FORTUNE — The occasional doubts that crop up over Warren Buffett’s investment prowess were laid to rest this week — again — by, of all companies, Harley-Davidson, Inc. HOG , the iconic Milwaukee motorcycle maker.

A business deal struck five years ago between the two renowned Midwestern entities — Buffett’s Berkshire Hathaway brk.a , in Omaha, and Harley-Davidson — infused $303 million into the motorcycle maker to help keep loans available to purchasers and dealers as credit markets sank along with the economy. The interest rate: 15%.

Harley-Davidson paid back the loan in February, said chief financial officer John Olin during a conference call this week announcing its first-quarter earnings.

The company took the high-interest loan, Olin said, to help finance buyers and keep its production lines and dealerships operating. It was the only way, he said. This way, the company — which was founded in Wisconsin just after the turn of the 20th century — could borrow money and, at the same time, keep its ownership intact.

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“It was the bridge we needed to get us through a rough time,” Olin said. Between 2007 and 2009, sales of Harley’s classic motorcycles — celebrated for their heavyweight, outlaw biker image — plummeted, down as much as 50% in the United States, as people had far less disposable income for purchases, or even for gasoline.

As the company began to climb back from the near-abyss, it wanted to repay its high-interest loan ahead of schedule, but Berkshire Hathaway struck a harder bargain, sticking with the handsome five-year loan terms, according to Harley-Davidson. No wonder, as the loan earned millions for Buffett, who already had chalked up a stellar windfall by investing a whopping $5 billion in shares of Goldman Sachs GS as the financial system teetered in the fall of 2008.

That loan had a 10% interest rate, and, like the Harley loan, came at a key time for the investment bank, which repaid the loan in 2011 — after paying about $500 million in interest.

While the loan to Harley-Davidson was also highly lucrative for Berkshire Hathaway, it drew much less attention than the one issued to Goldman Sachs, which became part of a key insider trading trial in which prosecutors accused former Goldman board member Rajat Gupta of helping hedge fund founder Raj Rajaratnam make $1 million by tipping him off to the Berkshire infusion before it became public.

Berkshire Hathaway — which has taken stakes in other noted American brands like Coca-Cola KO , and always on good repayment terms — invested $300 million in the troubled chopper manufacturer in 2009. At the same time, Davis Selected Advisers LP, Harley-Davidson’s biggest shareholder, also sank $300 million in unsecured loans into the company.

Despite twists and economic downturns as far back as the Great Depression of the 1930s, and then the onslaught from Japanese motorcycle makers in the 1970s and 1980s, Harley-Davidson celebrated its 110th anniversary last year — on the upswing.

Its iconic status seems to be intact. A 2013 Harley-Davidson given to Pope Francis last year by a grandson of the company’s founder to mark the company’s anniversary was sold recently for $327,000 at a Paris auction. Its regular price tag: around $16,000.

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In its most recent earnings report, Harley said that it sold 57,415 motorcycles worldwide during the first quarter of 2014, a 5.8% increase over the same quarter last year. This boosted total company revenue by 10%, with earnings up by 22%.

Much of the growth came from international sales, which increased 10.9% over the prior year. Sales in the United States grew by 3% as the company, accustomed to marketing to middle-aged men, made inroads among women, African-American, and Hispanic consumers.

The company also won over buyers by releasing new models that dovetail with its reputation for retro styling. After a five-year hiatus, it brought back the Low Rider — a remake of the original first introduced in 1977 — and other models for urban riding and long-distance touring.