They tested the dimple theory on Myth Busters(if I recall correctly). They covered a car in clay, tested MPG, then cut dimples into the clay and tested it again. They found an increase in MPG.
Fighter jets don't have dimples...i think there was a test plane once with thousands of holes drilled into the wings... No significant performance increase at all...much maintenance though as all those holes needed cleaning after every flight.
Dimpled helmets EH? Oh, yeah it's been done. https://www.rideapart.com/articles/255508/when-motorcycle-helmets-look-like-golf-balls/
in racing, helmets likely see unmodified flow only during braking when the rider pops up. dimples might make a measurable difference then... but you want to slow down so whats the point. all other times, the helmet is likely already getting modified somewhat turbulent air. so theres probably no need for dimples. we cant forget about relative magnitudes here. dimples on a golfball reduce drag by a significant percentage, maybe as high as 50%. this has a comparable effect in performance because drag is the primary component. there no way in hell dimples on a motorcycle or helmet will have anywhere close to that affect. id guess a 0.1% change in drag (or less), which is an even smaller performance change because theres so much more that goes into racing performance. if Yamaha had the choice of spending 100 man-hours researching and implementing dimples vs increase their engine performance, they absolutely should go with engine performance.
You're lacking capitalist imagination..."Three wacks for a dollar!" It's amazing how difficult it is to damage a motorcycle with a sledge hammer, but one toss down the track and they virtually explode. Kinda gives ya an insight to the forces at work...
Enzo Ferrari would agree - "Aerodynamics are for people that can't build engines." You might want to have chosen a different manufacturer to make your point, tho'.
That wasn't quite the same as dimples. They were trying to control the boundary layer and keep the flow attached though. https://en.wikipedia.org/wiki/Boundary_layer_suction
We know Yamaha's engine performance is teh suk right now. That was the point though. In racing, it is often better to improve your disadvantages over furthering your advantages as that will gain more performance due to diminishing returns. Pursuing an unknown might be worse, or you could get lucky and it could be better.