C'mon, stop exaggerating. The over-carbbed, over-cammed, under-muffled Harleys around here that pop, misfire and backfire their way around town would be lucky to get to 25% efficiency.
But it's not about having a machine that actually runs right, it's all about the "image."
Ever listen to your basic Harley idle? I mean, the reason it speeds up and slows down is that the two pistons are hitting top at nearly the same time and then you have three more engine cycles before they do it again. That’s why the basic idle sounds like “b-Bang, WHIRR- whir, b-BANG, WHIRR-whir....” They could at least have the decency to make it a two stroke so they don’t have three dead engine cycles between hits....