"Halftime Report" trader Jon Najarian spotted some unusual options activity in the company. He said other traders "were aggressively trading July options, so it's probably something very short term."
Najarian also said that there was a lot of volume in the stock both last Friday and this past Monday. He said, however, he isn't sure if the deal will actually happen.
Trader Jim Lebenthal advised investors holding Harley-Davidson to "see this rumor to play out, otherwise there's really no justification for it being up 12 percent."
Trader Josh Brown said that in order for the stock to find support, Harley-Davidson needs better sales overseas in Asia and Europe.
"The global thing was why you owned Harley-Davidson over the last few years and it didn't work. Stock was $70 in 2014 and you just saw that whole idea of global growth vanish and nothing's really replaced it," he said.
Harley-Davidson and KKR declined to comment.