The correct Yamaha G9 Fleet Master carburetor jet depends on the exact engine, carburetor and model year. Read the stamped main and pilot jets and match them to the correct service or parts specification.
G9 Fleet Master • Main & pilot jet sizes
G9 Fleet Master carburetor jet sizes at a glance
Main jet
Use the G9 carburetor ID; do not automatically install the G2 #106.3 main.
Pilot jet
Use the G9 carburetor ID; do not automatically install the G2 #72.5 pilot.
Altitude
Check the G9 parts or service specification for the exact carburetor ID and altitude.
Before ordering
Identify the engine and carburetor, then read the number stamped on the existing brass jet.
Lean symptoms
Needing choke, surging or load bog can also come from a clogged passage, weak fuel supply or intake leak.
Rich symptoms
Black smoke or plug fouling can also come from a stuck choke, high float level or leaking needle valve.
How to choose the correct Yamaha G9 Fleet Master jet
G9 Fleet Master jetting symptoms
Needs choke to run
Clean the pilot and main circuits and check fuel supply and an intake leak before fitting a larger jet.
Bogs under load
A restricted main jet can cause this, but so can weak pump flow, low bowl fuel level or a blocked filter.
Black smoke / fouled plug
Check choke position, float level and needle sealing before assuming the main jet is too large.
Runs well only at low speed
Main-jet or main-nozzle restriction becomes more likely once the pilot circuit is known to be clear.
Poor idle only
The pilot circuit matters much more than the main jet at idle.
High-altitude operation
Use the model-specific elevation chart where available; do not guess how many jet sizes to reduce.
G9 Fleet Master jet specifications
Applies to: Carbureted gasoline version.
Engine: Yamaha 4-stroke gasoline.
Carburetor: Yamaha/Mikuni carburetor; verify carb ID.
Main jet: Use the G9 carburetor ID; do not automatically install the G2 #106.3 main.
Pilot jet: Use the G9 carburetor ID; do not automatically install the G2 #72.5 pilot.
Altitude: Check the G9 parts or service specification for the exact carburetor ID and altitude.
Model-specific note
G9 is related to the later Yamaha/Mikuni carbureted family, but G2 jet numbers should not be copied without matching the G9 carburetor ID.
Yamaha G9 Fleet Master carburetor jet FAQ
What is the Yamaha G9 Fleet Master main jet size?
Use the G9 carburetor ID; do not automatically install the G2 #106.3 main. G9 is related to the later Yamaha/Mikuni carbureted family, but G2 jet numbers should not be copied without matching the G9 carburetor ID.
What is the Yamaha G9 Fleet Master pilot jet size?
Use the G9 carburetor ID; do not automatically install the G2 #72.5 pilot.
Does altitude change the Yamaha G9 Fleet Master main jet?
Check the G9 parts or service specification for the exact carburetor ID and altitude.
Can I install a larger jet in a Yamaha G9 Fleet Master?
Only after confirming the engine, carburetor, altitude and cause of the lean symptom. A clogged passage, intake leak or weak fuel supply should not be corrected with an oversized jet.
How do I identify the correct Yamaha G9 Fleet Master carburetor jet?
Use the stamped jet number together with the engine code, carburetor ID and model year. Cross-check those identifiers against the matching factory parts or service information.
What is the difference between the main and pilot jet on a Yamaha G9 Fleet Master?
The pilot circuit controls idle and very low-throttle fueling. The main jet becomes dominant as airflow, throttle opening and engine load increase.
Jet sizes can change with engine, carburetor revision, model year and altitude. This page applies to the carbureted gasoline version. Do not drill jets or assume a jet from another model is equivalent. Confirm the engine, carburetor ID and existing jet markings for your exact Yamaha G9 Fleet Master. For manufacturer documentation, visit the official manufacturer website.