Harley-Davidson riders in Europe don't care whether the iconic American motorcycles are made in the United States, custom motorcycle builder Alan Stulberg told CNBC.

"They’re concerned more about the pricing of the model as it compares to other options available in Europe," said Stulberg, co-founder of Revival Cycles, a motorcycle shop based in Austin, Texas, that restores vintage bikes and sells custom-built bikes starting at around $115,000.

"What [Harley-Davidson riders] are buying is the heritage of America-built," Stulberg said Thursday on "Squawk Alley." "But it being made in America isn’t really a priority."

Just two days earlier, President Donald Trump taunted Harley-Davidson on Twitter, saying, “Now that Harley-Davidson is moving part of its operation out of the U.S., my Administration is working with other Motor Cycle companies who want to move into the U.S. Harley customers are not happy with their move - sales are down 7% in 2017. The U.S. is where the Action is!"

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Full-year sales of Harley-Davidson motorcycles declined 7.2 percent in 2017, compared with the previous year. The iconic American motorcycle company's U.S. retail motorcycle unit shipments also dropped 10.5 percent in the same time period. Meanwhile, sales of less expensive Japanese motorcycles, such as Honda, Kawasaki, Suzuki and Yamaha, as well as stylish Swedish bikes, increased.

But a combination of aging Harley riders and changing consumer preferences appears to be responsible for Harley-Davidson's sales decline in recent years — not the consumers' desire to buy made in America.

Kelly Yun of Minneapolis said it was her "love of riding" that motivated her to buy her Harley.

"I was in Ecuador and saw Harleys," she told CNBC. "I thought, that's great. It's kind of like a German car in the United States. I wouldn't care where it was made."

Stulberg pointed out that Harley-Davidson has been building motorcycles outside of the U.S. for some time, with manufacturing plants in Brazil, India, Australia and Thailand.

"This isn't a new thing for them," he said.