Yamaha - Pilot Jet #37.5 Carburetor Fuel Metering Component 7CU-E4142-37-A0. Overview. Pilot jets are small, but they make a big difference in how an engine behaves at idle and low throttle. When one gets clogged or worn, you'll notice it right away-rough idle, stalling, or sluggish response off the line. I've cleaned plenty, but sometimes replacing it is the only way to get things running right again. When it's dialed in, the engine idles smooth and transitions clean into throttle.. Key Features. • Low-Speed Fuel Control - Regulates fuel delivery at idle and low throttle for smooth operation.• Precision Sized Jet - Calibrated at 37.5 for accurate fuel-air mixture in carbureted systems.• OEM Fit and Threading - Installs cleanly into the carburetor without modification.• Improves Idle Stability - Helps eliminate stalling, hesitation, and uneven low-speed performance.. Engine & Boat Compatibility. Designed for Yamaha outboard engines equipped with carbureted fuel systems that utilize a p