There are a variety of different drive chain sizes that have been used on motorcycles and ATVs over the years. Fortunately, the sizing code has remained consistent throughout, and a three digit number is used (50 is often used as an abbreviation for 530). If the letter “H” appears after the number, it indicates that the chain is a heavy duty one with thicker pins and link plates. There may also be letters after the size code that indicate an O-ring or X-ring type of chain or other special features.
The first number indicates the pin-center to pin-center distance in eighths of an inch. The second and third numbers indicate the minimum inside distance from link plate to link plate in eightieths of an inch. See the chart below for more information.
|Chain Size||Pin to Pin||Plate to Plate|
|420||4/8 or 1/2″||20/80 or 1/4″|
|428||4/8 or 1/2″||28/80 or 7/20″|
|520||5/8″||20/80 or 1/4″|
|525||5/8″||25/80 or 5/16″|
|530||5/8″||30/80 or 3/8″|
|532||5/8″||32/80 or 2/5″|
|630||6/8 or 3/4″||30/80 or 3/8″|
|632||6/8 or 3/4″||32/80 or 2/5″|