The American V-twin cruiser motorcycle has always sold on character and culture. The low-slung stance and the thumping, rhythmic note of a big-displacement engine were just about the only prerequisites to justify the purchase of the quintessential American cruiser. There was, however, a second conversation, and a silent one, that happened a few years into ownership when the service intervals started stacking. A discussion that would center around the heat management limitations of air-cooling, showing up in gaskets, seals, and the service invoices.

Source: https://www.topspeed.com/american-cruiser-reliability-secret-owners-love/