Honda XR500 RFVC Thumper found in Los Feliz

 Simple, light and efficient, the Honda XR500 is an ideal beginners motorcycle
 The presence of a single spring, Pro-link rear shock means this bike is a 1983 or newer and had an oil-in frame dry stump and RFVC combustion chamber and twin 28mm carburetors

Honda RVFC or Radial Four Valve Combustion, splays the valves radially away from the bore's axis and creating a hemispherical combustion chamber when viewed from the engine's profile. The splayed valves arrangement allows quicker flame propagation across the combustion chamber, allowing the engine to produce more power at a given RPM. Additional benefits include better cooling and the engine's timing can be more radically advanced.