Kawasaki Flat Track
Polaris/Indian has ruled the roost in American dirt track racing the last couple of years with a purpose built flat track bike. I read where Bryan Smith has announced he will return to Kawasaki equipped machinery for 2019. I understand that they scan Ebay, Cycle Trader, etc. for wrecked Ninjas or Versys and buy them for the engine. Versys cams get swapped for Ninja cams and stiffer valve springs. I'm not sure what else they did but the little engines are rumored to make 90+ hp.
I also see where KTM will have a factory team in both singles (basically 450cc motocross bikes with flat track wheels/tires) and in Twins with their 790. Next year should be pretty competitive.
If you like sideways racing and can't catch them on broadcast TV, they show up on Youtube about a week or so after the broadcast.