Decode Harley Cylinder Casting Numbers

You will find casting codes on various parts of your Harley.

Different numbers are stamped in different locations on your Harley Davidson motorcycle. The Vehicle Identification Number is on the swingarm frame and on the crankcase. Numbers are also stamped on the cylinder. Some might think this is the parts number, but the three-part number stands for the casting number. Casting numbers indicate when the part was cast or manufactured. This lets you know how old the part is. It is possible to have parts with different casting numbers.


1. Look closely at the casting numbers on your Harley cylinder; find a letter and two numbers. Note the two dashes. One comes after the letter, and one after the first number.

2. Determine where the letter falls in the alphabet. The letter “B” is the second letter of the alphabet. On a Harley that signifies February, the second month of the year. This is the month the Harley was manufactured.

3. Look at the first number. It indicates the day of the month the motorcycle was made. The second number indicates the year it was manufactured.