the gap for a Harley plug on a 88c.i. is 30
.040
.040 or 40 thousandths
.037"-.043" using any spark plug gap gauge. I have a 93 heritage softail classic and that is what is recommended.
40
.040"
Use a dime to gap the plug. If u haven't got a dime use two nickles
The proper plug gap is 0.038-0.043 Mike
.40
.040 in. RA8CH
.040, or 40 thousandths
The proper air gap is .032 to .036 depending on spark plug brand.
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.