TUSK Cold Start Jet Kit for Kawasaki KLX140R/KLX140 Main & Pilot Jets 98/40 — Improved Cold Starts & Low-Speed Throttle

Tusk Cold Start Jet Kit replaces factory pilot and main jets to improve cold-start behavior and low-speed throttle control on compatible KLX140 series carburetors.

When temperatures drop or after long idle periods, small-block carburetors on Kawasaki KLX140R F/L (2021–2026) and KLX140/L (2008–2020) can be slow to return crisp throttle response and stable idle. The Tusk Cold Start Jet Kit offers a simple, reversible carburetor adjustment—two replacement jets sized to refine fuel metering during warm-up without changing the carburetor body. Built from durable materials for direct fitment, this kit targets riders who want fewer choke cycles and steadier low-speed performance on trail and recreational rides.

How will these jets change cold starts and choke use?

Installing the included jets shifts the fuel mixture during engine warm-up to reduce the amount of enrichment required from the choke. That often means the engine reaches a stable idle sooner and the rider spends less time running the choke or blipping the throttle to clear a rich condition. Results vary with altitude, ambient temperature and carburetor condition, but the intent is more consistent starts under typical trail conditions.

• Includes a slightly leaner pilot jet for crisper idle as the engine warms.
• Main jet re-sizing improves throttle response during first minutes of operation.
• Helps shorten choke run time in most mild to moderate temperature ranges.

Will installation require special tools or tuning experience?

Basic hand tools and a modest level of mechanical comfort are sufficient to swap these jets into most compatible carburetors. Removal and replacement are straightforward: drain fuel or block the petcock, remove the float bowl, and change the jets with the correct driver. If you haven’t serviced a carburetor before, a Tusk Carburetor Rebuild Kit and a mini carb tool kit can make the job easier and help ensure proper sealing.

• Direct-replacement sizing requires no custom modifications to the carb body.
• Standard screwdrivers or jet drivers handle the swap; no special equipment needed.
• Pair with a Tusk rebuild kit for worn gaskets, seals, and a complete refresh.

What exact jet sizes are included and why do they matter?

The kit contains a 98 main jet and a 40 pilot jet selected to alter fuel delivery characteristics at both idle/low-speed and part-throttle conditions. The pilot jet governs mixture at idle and just off-idle, while the main jet affects mid- to high-throttle fueling. Choosing the correct sizes helps the carburetor run more predictably until the engine reaches normal operating temperature.

• 98 main jet for improved mid-throttle progression during warm-up.
• 40 pilot jet for a more stable idle and reduced bogging at low speeds.
• Sized to work as a straightforward tune for KLX140-compatible carburetors.

Are there regulatory or compatibility notes I should know?

This jet kit is intended for off-road and recreational use on compatible carburetors and is not CARB compliant for certain emissions-controlled applications. Confirm model-year compatibility (Kawasaki KLX140R F/L 2021–2026 and KLX140/L 2008–2020) and ensure your carburetor accepts standard pilot and main jet sizes. If your motorcycle must meet specific emissions regulations, check local rules before modifying fuel-system components.

• Non-CARB compliant—check local emissions requirements before installation.
• Designed as a swap-in for compatible stock carburetor jet locations.
• Pair with maintenance items for best long-term performance.

Who is this for: The Tusk Cold Start Jet Kit is aimed at KLX140 owners and recreational riders who want a simple, reversible upgrade to reduce choke time and improve low-speed drivability during engine warm-up. It’s best for riders comfortable with basic carburetor service or those planning a tune-up using Tusk’s rebuild and tool kits. If you ride trails, practice in variable temperatures, or simply want a more dependable cold-start routine, this kit is a low-cost, straightforward option.