Aren't the emissions standards with bikes different to cars? From my basic understanding with cars it's kind of like an average amongst all the models that the manufacturer sells, so the electric ones make up for the less efficient ones. With bikes, at least in Europe, they all have to meet a certain standard to be sold. You can't just have a bunch of super efficient 125s so that you can have a less efficient litre bike. I could be wrong though, I haven't done any research on the matter.
That is a good question. I wonder if Honda gets to fold in their motorcycle production into their auto production when averaging their emission and efficiency output? However, I have a suspicion that motorcycle manufacturers can average out their efficient models with their less and much more powerful models. A company like Honda builds a lot of small low-power motorcycles and also some powerful sport bikes that would seem to pollute much more than their small models. I just don't know. 
However, I do recall that Energica said that they were able to cut the price of their bikes when they were first introduced into California by about 1/3 due to their ability to sell their EV pollution credits on the state's "cap and trade" emission market.
I doubt there's any interaction between Honda's cars and bikes, or BMW, or Suzuki (do they still make cars?). They not even the same companies, just owned by the same parent company. I can't imagine there's any advantage to having small efficient bikes in the line up either or else you'd see companies like Triumph, Ducati, Harley, Moto-Guzzi, and many others coming out with 125s or similar instead of just sticking to big bikes.
It seems that the companies that do make the smaller bikes in addition to the bigger ones are the really big Japanese ones who have a history of making smaller bikes before emissions were even a big concern (Suzuki, Yamaha, Honda, Kawasaki) or the European ones who benefit greatly from the Euro licencing system (KTM, Aprilia, BMW with their 310).
