Honda TRX400EX / TRX400X (2005–2014) — 87 mm Big Bore Complete Engine & Cylinder Head Rebuild Kit

🛠️ Description

Build a stronger, pump-gas 400EX/400X with this complete 87 mm big bore package. Includes new cylinder and head, forged piston, Stage 2 cam, HD bottom-end components, and all gaskets and seals. Bolt-on design with no case or head machining required.

✅ What’s Included

• Works on all 2005+ Honda 400EX and 400X models

• 87 mm cylinder

• 87 mm big bore Wiseco or Wossner forged piston

• Nitride-coated piston rings (aka nitrite-coated)

• Chrome wrist pin

• Circlips

• Cylinder head with valve cover

• HD crankshaft assembly with rod

• Crank bearings

• Crank balancer bearings

• Transmission bearings

• Clutch bearings

• Shift cam bearings

• Camshaft bearings

• Stage 2 replacement camshaft

• HD cam chain

• Cam chain guides

• Black billet cam chain tensioner

• Complete gasket kit

• Cometic big bore MLS head gasket

• Seal kit

• Clutch kit

• Talon TITANIUM cylinder head stud kit — Lifetime warranty*

• NGK spark plug

• No case or head mods required

• Runs on pump or race gas

• 1-year warranty on all new parts*

📦 Fitment

• Honda TRX400EX: 2005–2008

• Honda TRX400X: 2009–2014
  (Not intended for 1999–2004 models.)

🛡️ Warranty Info

• All parts are new and carry a 1-year limited warranty from the original manufacturers.

• Talon titanium stud kit includes a lifetime warranty.

• Returns accepted on new, uninstalled items only. Professional installation recommended.

🔑 Key Features

• ~416 cc displacement using 87 mm bore

• Forged piston for strength and heat control

• Stage 2 cam for midrange pull and stronger top end

• HD crank and bearings for durability

• MLS head gasket and titanium studs for superior sealing

• Runs on 91-octane pump gas with proper jetting and tune