.037"-.043" using any spark plug gap gauge. I have a 93 heritage softail classic and that is what is recommended.
The proper air gap is .032 to .036 depending on spark plug brand.
40
the gap for a Harley plug on a 88c.i. is 30
The proper plug gap is 0.038-0.043 Mike
.040, or 40 thousandths
.040 in. RA8CH
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"
.040 is rcommended gap .040
40
The recommended spark plug gap for a 1996 Harley Davidson 883 Sportster is .040. That is the most common gap for most Harley Davidson engines.
Ngk recommend NGKBCPR7E with a gap of 1.0mm. Check www.aprilia-merseyside for further assistance.