Honda 400EX / 400X 88mm Big Bore Kit – Valves, Cam, Studs

🔥 88mm Big Bore Performance Kit – Honda TRX400EX / 400X / XR400R
Complete Bolt-On Power Package with Top-Tier Components

This 88mm big bore kit is designed to dramatically improve power, reliability, and airflow in your Honda 400EX, 400X, or XR400R — all without the need to machine your cases or cylinder head. Whether you're trail riding, racing, or rebuilding, this is the most comprehensive top-end upgrade kit available.

✅ Fits all 1999–2014 TRX400EX / 400X and 1996–2004 XR400R models
✅ Bolt-on installation – no head or case boring required
✅ Built with race-grade materials from trusted brands like Wiseco, Hotcams, Kibblewhite, and MaxLock

📦 What’s Included:

• 🧱 88mm Aftermarket Cylinder – Precision-cast, ready to install

• 🏁 Wiseco or JE Forged Big Bore Piston (based on availability)

• 🛠️ Nitrite Coated Piston Rings

• 🔩 Chrome Wristpin + Circlips

• 💪 MaxLock Titanium Head Stud Kit – Lifetime Warranty*

• 🧰 Cometic Top End Gasket Kit

• 🔧 MLS Big Bore Head Gasket

• ⚙️ Kibblewhite Lightweight Valve Spring Kit

• 🖤 Kibblewhite Black Diamond Intake & Exhaust Valves

• 🔒 Kibblewhite Viton Valve Stem Seals

• 🔩 Stage 2 Hotcam Camshaft

• ⚙️ Both Cam Bearings

• 🔗 Heavy Duty Timing Chain Conversion Kit

• 🎁 Stickers + Install Tips

⚙️ Key Features:

• ✅ No Machining Required – Direct fit to stock head and cases

• ✅ Built for Big Power – 88mm bore with forged piston + performance cam

• ✅ Valve + Spring Combo – Increased lift, durability, and top-end flow

• ✅ Titanium Stud Kit – Lifetime warranty + improved head sealing

• ✅ Pump or Race Gas Compatible

• ✅ All Parts Are Brand New – In original packaging, no core needed

📌 Fitment Compatibility:

📦 Shipping Time:
Ships within 3–5 business days. Tracking provided after fulfillment.

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