Unleash true race power from your Honda 400EX, 400X, or XR400R with this complete 440cc big bore top end rebuild kit. Featuring an 89mm forged piston, Stage 3 Hotcam, and HD cam chain, this high-compression setup is ideal for built motors running race gas only.
Everything is brand new in original packaging. No head or case mods required.
New 89mm Cylinder
Wiseco or JE 12.5:1 Forged Piston (Race Gas Only)
Nitrite-Coated High Temp Piston Rings
Chrome Wristpin & Circlips
Stage 3 Hotcam Camshaft
Cam Bearings (x2)
Maxlock Head Stud Kit (Lifetime Warranty)
Cometic MLS Big Bore Head Gasket
Complete Top End Gasket Kit (head, base, exhaust, chain tensioner)
Heavy-Duty Timing Chain
NGK Spark Plug
Stickers
Fits all:
Honda TRX400EX (1999–2008)
Honda TRX400X (2009, 2012–2014)
Honda XR400R (1996–2004)
Includes 1-year warranty on all components and lifetime warranty on Maxlock studs.
⚠️ Not DIY – must be installed by a qualified, experienced engine builder. Warranty is void for failures due to improper install, tuning, break-in, or misuse. All warranty claims require return of affected parts for inspection.
We ship next day most of the time. Modquad parts are shipped Monday-Thursday. Engine Kits are 3-5 business days.
We don't do backorder! If your items has already sold you will be notified immediately and you money refunded on the spot.
Sold items are removed daily.
If you see it on this website, it is 100% in stock unless it just sold before you clicked buy.
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