Depending on where you live in the world, you may or may not know about kerosene outboard motors. Kerosene outboard motors are popular in the third world because in some places kerosene costs less than half the price of gasoline. For example, in India and Sri Lanka where the fuel is subsidized (because it is used for cooking and lighting), kerosene costs a mere 1/3 the price of gasoline. So naturally it follows, operating costs are significantly lower with a kerosene outboard motor.
About 16 years ago Yamaha Marine developed its kerosene outboard motors because of the demand within the Sri Lankan market where fishing villages such as Negombo have come to rely upon them. They start on gas, then transition to kerosene underway. Know that kerosene outboards are better suited for trolling or long hauls rather than for short trips. Kerosene burns at a higher temperature than gasoline and combustion is not as efficient. Exhaust smoke is copious.
Yamaha kerosene outboards are founded upon the Yamaha Enduro, a carbureted two-stroke outboard motor series developed for commercial use (long hours of continuous operation) on small fishing boats and passenger vessels. Yamaha Enduro outboards boast enhanced strength and durability in the roller bearings, crankshaft and cylinder block, as well as an improved (chrome-plated) water pump.