99103-MA1-0380 Slow (#38) Jet - Overview. The 99103-MA1-0380 Slow (#38) Jet is an essential component within the fuel system of Honda marine engines. This slow jet controls the fuel-air mixture during low engine speeds and idle, ensuring reliable engine operation and performance. Designed to precise OEM specifications, it seamlessly integrates with existing engine components, maintaining optimal functionality and durability in demanding marine environments.. Key Features. Controls fuel flow at l