.040
the gap for a Harley plug on a 88c.i. is 30
.040 or 40 thousandths
The spark plug gap for a 1994 Harley-Davidson Softail Heritage is typically set at 0.040 inches (1.0 mm). It's always a good idea to check your owner's manual or service manual for the specific model to confirm this specification. Proper gap adjustment is crucial for optimal engine performance and efficiency.
Use a dime to gap the plug. If u haven't got a dime use two nickles
.040"
.037"-.043" using any spark plug gap gauge. I have a 93 heritage softail classic and that is what is recommended.
.40
.040, or 40 thousandths
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 suggested spark plug gap for a 1973 Harley Davidson is 0.040. It is the suggested gap for most of the spark plugs of that era.
.040"
.038" to .043"