400EX 400X XR400 89m 440 Big Bore Kit Stage 3 Hotcam 1051-3 Cam Top End Redo Kit

Honda TRX400EX 400X XR400 89mm 440 Big Bore Kit Stage 3 Hot Cam Complete Top End Rebuild

📖 Product Description

The BPRATV 89mm 440cc Big Bore Kit with Stage 3 Hot Cam is the ultimate high-performance top end rebuild for your Honda TRX400EX, TRX400X, or XR400. Designed for riders who demand brutal torque, aggressive throttle response, and race-inspired acceleration, this complete kit transforms your stock 400 into a hard-pulling 440cc powerhouse built for competition.

🔥 Key Features & Complete Kit Contents

This is a true complete top end redo kit — not a partial rebuild. Every critical performance component is included so you can rebuild with confidence using premium parts from BPRATV, Wiseco, Wossner, JE, CP, Cometic, SKF, NGK, Hot Cams, and Maxlock.

• BPRATV 89mm aftermarket big bore cylinder (440cc conversion)
• Forged piston kit (Wiseco, Wossner, JE, or CP based on availability) with high-temp rings, chrome wristpin & circlips
• Cometic complete top end gasket kit
• Cometic MLS 89mm big bore head gasket
• Hot Cams Stage 3 camshaft for aggressive mid-to-top end gains
• BPRATV Talon Heavy Duty cam chain (thicker & wider than OEM)
• SKF cam bearings (both included)
• Maxlock Titanium head stud kit – Lifetime Warranty
• New NGK spark plug to ensure proper ignition on startup

⚙️ Fitment & Performance Compatibility

Engineered as a direct-fit performance upgrade for Honda’s legendary air-cooled 400 platform.

• Honda TRX400EX – All Years
• Honda TRX400X – All Years
• Honda XR400 – All Years
• 397cc air-cooled Honda 400 engine platform
• Closed-course competition and racing applications

❓ Frequently Asked Questions (FAQ)

• Q: Is this everything needed for a full top end rebuild?

  A: Yes. This kit includes the 89mm cylinder, forged piston kit, rings, wristpin, circlips, full Cometic gasket kit, MLS head gasket, Stage 3 camshaft, heavy-duty cam chain, SKF cam bearings, titanium head studs, and NGK spark plug.

• Q: Which forged piston brand will I receive?

  A: Pistons are supplied from Wiseco, Wossner, JE, or CP depending on current inventory. You are welcome to contact us with a preference before ordering, but we cannot guarantee a specific brand — only what is currently in stock.

• Q: Will this increase horsepower and torque?

  A: Absolutely. The 440cc big bore combined with the Stage 3 camshaft significantly increases bottom-end torque, midrange pull, and top-end horsepower.

• Q: Is the cam chain upgraded from OEM?

  A: Yes. Our BPRATV Talon Heavy Duty cam chain is thicker and wider than OEM chains for added durability under high-performance loads.

🌟 Why Buy from BPRATV? Trusted Honda Performance Experts 🌟

At BPRATV, our promise is unwavering: The Best Parts. The Best Performance. We specialize in high-performance Honda ATV and dirt bike engine builds and ship premium 400EX rebuild kits fast — often by the next business day. No one sells more high-quality 400EX rebuild kits. Trust BPRATV to keep your Honda TRX400EX, TRX400X, or XR400 running at its best, every single time.

Build it right. Build it once. Upgrade to 440cc power today!

BPRATV - The Best Parts. The Best Performance. The Best Price.

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© BPRATV LLC 1-year limited warranty from the manufacturer for material or workmanship defects.*

Due to the nature of high performance and racing applications, BPRATV LLC components are sold without express warranty or any implied warranty of merchantability or fitness for a specific purpose. BPRATV LLC shall not, under any circumstances, be liable for any specific, incidental or consequential damages, including, but not limited to, damage, or loss of property or equipment, loss of profits or revenue(s), cost of purchased or replacement goods, or claims of customers of the purpose, which may arise and/or shall result from sale, installation or use of these parts. Installation of these parts may void vehicle manufacturers warranty coverage and/or may cause the vehicle to be illegal in some locations.

This product is exempt from the emission standards and related requirements of 40 C.F.R. § 1051 as provided by 40 C.F.R. § 1051.620, and California law [e.g., vehicle code§§ 27156 and 38391]. This product is sold only for use in connection with EPA-certified, purpose-built, nonroad vehicles used solely for closed course, nonroad competition/racing and not used for any recreational purpose or on public highways or rights of way maintained by and open to the public. This product is sold only in connection with machines that do not fall under state and/or federal noise or emission standards/regulations. Purchasers who purchase this product represent and warrant that the product is purchased only in connection with EPA-certified, emission-regulations-exempt and noise-regulations-exempt competition/racing vehicles as interpreted under applicable state and/or federal law.