TRX400EX 89mm Big Bore Engine Rebuild Kit – 1999–2004

SKU 284841906561

🔧 Complete Engine Rebuild Kit – 89mm Big Bore | Honda TRX400EX (1999–2004)
Bolt-On Power. No Case Mods Required. All Parts Brand New.

This comprehensive 89mm big bore rebuild kit is engineered for performance, reliability, and ease of installation. Featuring forged internals, a Stage 3 camshaft, and lifetime warranty titanium studs, this package is perfect for trail, dune, or race builds.

✅ Fits all 1999–2004 Honda TRX400EX 2x4 models
✅ No case machining required – true bolt-on solution
✅ 1-Year Warranty on all components

📦 What’s Included:

• ✔️ 89mm Aftermarket Cylinder

• ✔️ Forged Piston (Wiseco, CP, or JE – based on availability)

• ✔️ Nitrite-Coated Piston Rings

• ✔️ Chrome Wristpin & Circlips

• ✔️ Hotrods or Wiseco Heavy-Duty Crankshaft w/ Rod

• ✔️ Hotcams Stage 3 Camshaft

• ✔️ Main Bearings + Transmission Bearings

• ✔️ Cam Bearings

• ✔️ MAXLOCK Titanium Head Stud Kit – Lifetime Warranty*

• ✔️ Complete Gasket Kit + Cometic MLS Head Gasket

• ✔️ Full Engine Oil Seal Kit

• ✔️ Valve Stem Seals

• ✔️ Heavy-Duty Cam Chain

• ✔️ Complete Clutch Kit (fibers, steels, springs)

• ✔️ Stickers Included

⚙️ Key Features:

• 🧰 Full Top and Bottom End Coverage

• 🔧 No Case Mods Needed – Drop-in ready

• 💥 Stage 3 Cam for Maximum Performance

• 🔩 Titanium Stud Kit for Improved Clamping Force

• 🛠️ Built to Handle Pump or Race Gas

• 📦 All Items Brand New – No Cores Required

✅ Fitment:

• 1999 Honda TRX400EX 2x4

• 2000 Honda TRX400EX 2x4

• 2001 Honda TRX400EX 2x4

• 2002 Honda TRX400EX 2x4

• 2003 Honda TRX400EX 2x4

• 2004 Honda TRX400EX 2x4

⚠️ Warranty Notice:

This product is not intended for DIY installation.
Engine assembly requires accurate measurement, proper ring gap setting, and torque specs.
All claims require parts to be returned for professional inspection. Warranty covers part defects only — not labor, misuse, tuning, or installation errors.

📦 Shipping Time:
Ships within 5–7 business days. Tracking provided upon fulfillment.

💬 Customer Support:
Available Monday–Friday, 7 AM to 4 PM PST
24/7 live store chat available