Jets
What Are Carburetor Jets and Why Do They Matter?
Carburetor jets are small but critically important metering components that control how much fuel enters the air-fuel mixture inside a carburetor. Essentially precision-drilled orifices, jets are the primary tuning variable in any carbureted engine — whether that's a lawn mower, a motorcycle, a vintage muscle car, or an off-road vehicle. The diameter of the jet's hole dictates fuel flow: too small and the engine runs lean (too little fuel), risking overheating and power loss; too large and it runs rich (too much fuel), causing rough idle, poor economy, and fouled plugs.
Jets are a core part of carburetor tuning and maintenance. Over time, jets can become clogged with varnish deposits from stale fuel, corroded, or simply worn — all of which disrupt the calibrated fuel flow the engine needs. Replacing or re-jetting a carburetor is one of the most accessible and cost-effective ways to restore proper engine performance, optimize for a specific altitude, account for an intake or exhaust upgrade, or dial in a competition tune.
Types of Carburetor Jets
- Main Jets – Control fuel delivery at mid to full throttle. These are the most commonly replaced and tuned jets.
- Pilot Jets (Slow Jets) – Govern fuel flow at idle and low throttle openings, critical for smooth starts and off-idle response.
- Needle Jets – Work in combination with the jet needle to meter fuel through the mid-range throttle positions.
- Air Jets – Meter air rather than fuel, blending it into the emulsion tube to create a fine fuel mist for efficient combustion.
What to Consider When Shopping for Jets
Selecting the right jet starts with knowing your carburetor make and model — jets are not universally interchangeable. Thread pitch, body diameter, and orifice size all vary between manufacturers. If you're re-jetting for performance or altitude changes, a jet kit that includes a range of sizes is often the smarter investment over a single replacement. Always verify OEM specifications before ordering, and consider the full system (intake, exhaust, elevation) when sizing up or down.
Top Brands in Carburetor Jets
Briggs & Stratton is the go-to source for jets used in small engines powering lawn mowers, generators, and outdoor power equipment. Their OEM jets are engineered to exact factory tolerances, making them the reliable choice for restoring a Briggs-powered machine to like-new fuel delivery performance.
Mikuni is a legendary name in motorcycle and powersports carburetors, and their jets are equally well-regarded. Mikuni offers an extensive range of main jets, pilot jets, and needle jets compatible with their popular VM, TM, and BST carburetor series — a staple for both OEM replacement and performance tuning.
EBC carries a broad selection of jets spanning a wide variety of applications, making them a versatile option when sourcing hard-to-find sizes for less common carburetors. Their large product catalog ensures coverage across many engine platforms.
Holley is an iconic American carburetor brand whose jets are a cornerstone of V8 performance tuning. Holley jets are precision-machined and available in an expansive range of sizes, making them essential for anyone building or fine-tuning a Holley 2-barrel or 4-barrel carburetor setup.
Weber Carburetor jets are a must for enthusiasts running Weber DCOE, IDF, or DGAV carburetors on European sports cars and modified imports. Weber's jet range allows precise calibration of these highly tunable carburetors for street and track use.