I get the feeling that Zero makes a very
conservative guess how many motorcycles they
might be able to sell each year and orders parts for their new models from their Chinese suppliers accordingly. Then they build all of the bikes they can before the supply of the parts runs out and ships them to dealers. After that they shut down the assembly line and call it a year, while their engineering staff continue to design future models and management starts ordering more parts for the following year's models. But if they guess wrong and sales are stronger than they predicted, the product pipeline empties and potentially those sales.
My
observation is that the Zero investors really don't want to take any financial risks and are very adverse about having more product than they can sell during a model year and potentially needing to offer discounts to get rid of the old models, which has certainly happened in the past. And that would be my
guess why the 2018 FXS model supply has dried up for this year. With large institutional orders coming in, I think we can assume that Zero will be more optimistic in their parts ordering for the 2019 model year. Of course, the current trade situation and rising interest rates are no doubt also making them shake in their financial boots right now.