The crash happened Thursday, Aug. 20 at around 6:30 a.m. on Sunrise Highway (Route 27), in Shirley, approximately one-quarter of a mile east of William Floyd Parkway.
The collision also involved a 2005 Toyota Sequoia traveling eastbound, Suffolk County Police said.
The motorcyclist is currently unconscious at Long Island Community Hospital in East Patchogue.
The driver of the SUV, Jean Cassamajor of North Babylon, 54, was uninjured and no charges were filed.
Both Cassamajor's vehicle and the 2017 Kawasaki Ninja belonging to the unidentified man have been impounded as evidence and for safety checks.
Anyone who bore witness to the crash is asked to call detectives at 631-852-8752.
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