What differences make a dirt bike’s engine sound high-pitched and tinny, but something like a Harley-Davidson’s engine sound deep and rumbly?

Question

Edit: I’m referring more to those heavy cruising bikes than specifically Harleys, but it seems the engine traits are similar enough anyway.

So from what I’m getting from the answers, the reason heavy cruising bikes sound so deep compared to dirtbikes is primarily the resonance due to engine size as well as being a four-stroke design. And since the extra tinny-sounding two-strokes aren’t much of a thing anymore, it’s mostly due to engine size now. (With some influence from muffler design.)

Thanks for the answers!

In: Technology

Answer 1

Adding to what others have already said, rev range and displacement. (piston/cylinder size). 2 stroke dirt bikes have much smaller engine parts, and you can spin them faster before you start to run into problems.

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Harley motors are much bigger, and more reciprocating mass means lower rev ranges.