When Dr. Marcus Sommers realizes that he and his troubled, estranged brother David may be prone a fatal brain disease that runs in their family, he decides to make peace with his sibling, and invites him on a trip to the Rockies. There, the brothers bond over their shared enthusiasm for cycling and decide to enter a grueling bike race through the mountains. However, Marcus' health soon begins to fail, and David must compete without his brother at his side.
1979 Suzuki GS 1000 S "Wes Cooley Replica"
Just for that back mudguard and (possibly) a drum front brake, I think this is a Kawasaki KZ 400, some of the poverty spec ones came with a factory 2:1 exhaust.
K 100 RT? Or maybe a model with a smaller engine.
BMW R 100 RT