West Yorkshire Police were called at 4.19pm. The ambulance service are also on the sceneand the air ambulance attended.
There are no further details on the condition of the motorcyclist at this time.
It happened between Foundry Lane Burger King and Seacroft Hospital on the A64.
Arriva Yorkshire said that, all 166 services will be diverting via the 163 route in both directions between Halton Dial and Cross Gates until further notice.
The road is likely to be closed for some time, according to police.