When changing the spark plugs of a vehicle a person has to gap the plugs at the right size. The spark plug gap for a 2003 Heritage Softail is .036 inches.Ê
.038" to .043"
.040 or 40 thousandths
Use a dime to gap the plug. If u haven't got a dime use two nickles
.037"-.043" using any spark plug gap gauge. I have a 93 heritage softail classic and that is what is recommended.
.040"
Twin Cams take a 12mm thread diameter plug. All Harleys with electronic ignition require a .040 plug gap.
When changing the spark plugs on any vehicle, the person must leave the right gap size. The 1999 Harley Softail has a spark plug gap size of .040 inches.
.40
the gap for a Harley plug on a 88c.i. is 30
.040
40 to 45 on the gauge. 40 is normal