The robbery occurred near the car park in Torrisholme Road at around 9pm on Sunday (February 27).
Police said the two offenders approached a man on an e-scooter before threatening him with a kitchen knife.
The men then stole the victim's Kawasaki KX250F before making off from the scene over a bridge which leads to Ryelands Estate.
On Monday (February 28), police launched an appeal for witnesses and released a picture of the stolen motorcycle.
A spokesman for Lancashire Police said: "If you were in the area at the time and witnessed anything that could assist with our enquiry then could you contact us.
"If you see this bike or know of its whereabouts can you also get in touch."
The offenders are described as being male and were both wearing black clothing.
The knifeman was wearing a black Armani puffer style jacket.
The victim's Kawasaki KX250F has the number 16 on the front and side, police said.
Anyone with information can contact the police by calling 101 or emailing [email protected], quoting log number LC-20220227-1565.
Alternatively, independent charity Crimestoppers can be contacted anonymously on 0800 555 111 or online at https://crimestoppers-uk.org/.
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