Why isn't there any motor bike that can run on CNG, LPG or Diesel?

Diesel has been noted, a couple do exist and the Indian market and Europe has some. CNG, LPG? India has some 2 wheel specials, more 3 wheelers. In US the articles note that they are home conversions often using the LP gas equipment for generators or small forklifts. The 20 pound cylinders available at some stations are used most frequently- a pragmatic fuel available choice. The large tank refillables on the trike conversions are similar to the tractor, forklift tank systems. As for factory LPG, CNG? 2 wheelers bigger than a couple scooters used in Mumbai seem to be very few.