In the world of Harley-Davidson Ironhead Sportsters, the years 1977 through 1985 (often referred to as the "late-case" era) are a minefield of subtle changes. The YR104 is one of the most significant casting numbers you’ll encounter, specifically identifying a set of produced in the late 1970s and early 1980s.
In real-world testing, the YR104 handles: mib yr104
Usually supports up to 28V or 45V (depending on the specific sub-model/revision), making it suitable for single cells and small battery packs. In the world of Harley-Davidson Ironhead Sportsters, the