Moose Offroad 1003‑1867 Hot Start Plunger Rebuild Kit – Fits Yamaha YZ250F, YZ450F, WR250F & WR450F

OVERVIEW

The MOOSE RACING Plunger Rebuild Kit provides the precise O-rings, springs, and hardware needed to restore proper choke-plunger function in Yamaha carburetors. This kit replaces sealed internal components that degrade over time, ensuring consistent fuel-air mixture control and reliable engine operation. Manufactured for direct fitment on YZ and WR series dirt bikes, it maintains the structural integrity of your carburetor’s hot-start system.

ENGINEERING & PERFORMANCE

The kit includes targeted replacement parts that prevent choke plungers from seizing or becoming lost during maintenance procedures. By installing fresh seals and springs, you restore consistent cold-start response and eliminate running conditions caused by worn internals. Each component is designed to match factory specifications, providing a direct replacement that keeps your carburetor calibrated for optimal airflow and fuel delivery throughout service intervals.

KEY FEATURES

• Includes essential O-rings, compression springs, retaining nut, boots, and cable guide
• Restores proper hot-start plunger operation in Yamaha carburetors
• Prevents choke plunger seizure or loss during overhauls
• Addresses hard starting and poor engine-running conditions
• Direct replacement for stock service components
• Compatible with multiple YZ and WR model generations
• Ensures reliable sealing and stable choke mechanism engagement
• Supports thorough carburetor rebuild procedures

TECHNICAL SPECIFICATIONS

• Brand: Moose Racing
• Part Name: Plunger Rebuild Kit Hot Start Yamaha
• Component Type: Carburetor plunger rebuild kit / service hardware
• Supported Years: 2003–2014 (model-dependent)
• Compatible Transports/Trims: Yamaha YZ 250F, YZ 450F, WR 250F, WR 450F

FITMENT

• Yamaha YZ 250F (2003–2013)
• Yamaha YZ 450F (2003–2009)
• Yamaha WR 250F (2003–2014)
• Yamaha WR 450F (2003–2011)

WHY RIDERS CHOOSE THIS

Riders choose this rebuild kit because it supplies every critical seal and spring required to fix cold-start issues without replacing entire carburetor assemblies. The included hardware maintains the original design tolerances, which keeps the choke plunger moving smoothly and prevents the leaks or binding that cause poor idle and difficult hot starts. Because it matches OEM geometry, the kit integrates cleanly with existing carburetors and supports quick, reliable recalibration after teardown. This focused solution gives off-road mechanics a dependable way to restore predictable fuel-mixture control while extending the service life of their engines.