When replacing the sprag bearing, you need to make sure the bearing race in the drive sprocket and the bearing race on the crank gear are not worn and dimensionally correct. The drive sprocket I.D. should be 2.281" and the crank gear O.D. should be 1.625". We do not have the correct tolerances, but within .001" should be adequate. The old sprag bearings came with 14 rollers, where the new ones come with 18 rollers and since the sprag bearing is normally a trouble spot with the starter system, it is recommended you upgrade to the new bearing if you have the old bearing.

For more information on the sprag bearing and how it fits into the starter assembly see our technical article: Pictorial help with installing the E-start starter gear train and setting up the backfire assembly.