Custer's Run: a Sci-fi Western Lrg edition

Pursued by Bud and his motorcycle gang in modern day Montana, Dee runs into David a Native American filmmaker on his way to the motorcycle rally in Sturgis. As David helps Dee escape the motorcycle gang they run into Og, a being from another time, who they mistake for a drunken dentist. Og gives them what they think is a lava lamp but is in fact a time travel device. When they motorcycle gang catches up with them they inadvertently trigger the device which sends them back to the time just before General George Armstrong Custer loses the battle of the Little Bighorn. While in the past David connects with his native forebears and he and Dee decide they must save the Sioux from the consequences of the upcoming battle.