Yamaha XS 650 or Yamaha SR 500 - Extraordinary Quality Swing Arms For Yamaha single and Twin - They can be used on TT or 1/2 mile track bikes. Main tubes are 1" x 2" .065 U.S.A c.r.e.w steel. Tubes are miter cut, then axle slot (.875 x 1.350) and notches are put in with a CNC mill. All parts are...