.40
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"
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.
Twin Cams take a 12mm thread diameter plug. All Harleys with electronic ignition require a .040 plug gap.
.40
the gap for a Harley plug on a 88c.i. is 30
.040
40 to 45 on the gauge. 40 is normal