The 110 is in extremely high demand and the YS factory is doing it's best to keep up, while still producing all of the other engines it makes.
It is not temporarily out of production, we are just between shipments again. More engines are supposed to ship around the end of this month. Normally it takes 2 to 3 weeks for shipments to reach us from Japan by the time ocean freight, customs and domestic delivery takes place. Figure on engines being in dealers hands by the end of February.

The 110 burns 1/4 to 1/2 oz more per minute than the 91 depending on the nitro content of the fuel used. Higher nitro=more consumption.