Buy a Factory Service Manual. Its in there.
040
.040
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
.40
.040"
.40
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.
The factory plug is HD PN 6R12- This is also available in the gold series plug. The factory plug is HD PN 6R12- This is also available in the gold series plug.
.040
40 to 45 on the gauge. 40 is normal
.038" to .043"
the gap for a Harley plug on a 88c.i. is 30
.040 or 40 thousandths