Engineered to meet or exceed Yamaha's top-end sealing standards, this Top End Gasket Kit is designed to restore compression and maintain engine integrity during top-end rebuilds. The aftermarket replacement quality ensures dependable performance across multiple YFM platforms, supporting reliable operation on Yamaha YFM350 and YFM400 families as well as Bruin, Big Bear, Grizzly, Kodiak, Raptor, Warrior, and Wolverine variants. All items are aftermarket replacement quality.

Comprehensive Vehicle Fitment

Product Specifications

OEM & Aftermarket Cross-Reference Information

OEM and aftermarket cross-reference numbers are provided for reference purposes only. These part numbers are commonly referenced for Yamaha top-end gasket sets and may appear across multiple aftermarket suppliers. Always verify fitment using your machine's exact model, year, and original part number before ordering.

What's Included

Based on standard top-end gasket kits for the YFM350 engine, this kit typically includes:

• Cylinder head gasket (replaces OEM 1UY-11181-01-00) 

• Cylinder base gasket (replaces OEM 4KB-11351-00-00) 

• Valve cover gasket

• Intake gaskets

• Exhaust gasket(s)

• Timing chain tensioner gasket 

• Assorted O-rings and seals as required for complete top-end sealing

Complete rebuild kits from NICHE and JINFANNIBI include additional components such as pistons, rings, wristpins, circlips, and spark plugs for comprehensive engine rebuilding .

Why Choose This Aftermarket Top End Gasket Kit?

• Broad Vehicle Coverage: Precision-engineered for a wide range of Yamaha YFM350 and YFM400 models spanning 1987 through 2014, including Big Bear, Kodiak, Bruin, Grizzly, Raptor, Warrior, Wolverine, and Moto-4 variants .

• OEM Cross-Reference: Cross-references genuine Yamaha part numbers 4KB-11351-00-00 (cylinder base gasket)  and 1UY-11181-01-00 (cylinder head gasket)  for confident replacement.

• Proven Aftermarket Support: Multiple respected aftermarket brands manufacture compatible gasket kits:

  • NICHE offers head and base gasket kits (519-KGS2221K) specifically designed for Yamaha 350/400 applications 

  • Wiseco delivers OEM+ quality gasket kits (WB1033) inspected for quality and accuracy 

  • JINFANNIBI provides complete top end rebuild kits with verified fitment across multiple YFM350 platforms 

• Comprehensive Fitment Confirmation: Multiple aftermarket suppliers confirm compatibility across the listed models, with consistent part number references across different brands .

• Restores Compression: New head and base gaskets ensure proper cylinder sealing for optimal engine performance.

• Prevents Leaks: Complete sealing kit prevents oil seepage and maintains clean engine operation.

Installation Notes:

• Ensure all mating surfaces are clean and free from old gasket material before installation.

• Follow manufacturer torque specifications and tightening sequences for cylinder head bolts.

• Use new gaskets only—do not reuse old gaskets once removed.

• Check valve clearance after head installation and adjust if necessary.

• Verify all components are properly seated before reassembling the top end.

• After installation, run the engine and check for any signs of leaks.

• For complete engine rebuilding, consider purchasing a full gasket kit that includes additional engine gaskets and seals .

Why Upgrade?
Worn or damaged gaskets can cause compression loss, oil leaks, and contamination—leading to poor performance and potential engine damage. Restore your Yamaha YFM350 or YFM400 engine's sealing integrity with this quality aftermarket top end gasket set, designed to keep you riding with confidence.

Order your top end gasket kit today and get back on the trail with confidence.