PROX Top End Gasket Kit (base + head) for YAMAHA WRF 450, YFZ 450, YZF 450 and GAS GAS ECF 450 2006-2025

The PROX (embase + culasse) 36.2406 top end gasket kit is designed for YAMAHA WRF 450, YFZ 450, YZF 450 and GAS GAS ECF 450 from 2006 to 2025. The top end gasket kit brings together the gaskets to replace every time the cylinder head or cylinder comes off. A gasket crushed by tightening never gets its shape back: refitting it means risking a compression, coolant or oil leak, and having to strip everything down again.

Specifications

• Brand: PROX
• Manufacturer part number: 36.2406
• Weight: 120 g
• Engine: 4-stroke

When to replace it?

• Coolant or oil seeping at the head/cylinder or cylinder/crankcase joint.
• Coolant level dropping, bubbles in the radiator.
• Hissing or black marks where the exhaust leaves the cylinder.

At every piston change and every time the cylinder head or cylinder is removed, even for a simple inspection. Gaskets cost little compared with the work of stripping the engine.

Fitting tips

1. Clean the gasket faces without scratching them (plastic scraper, solvent): they must be clean, dry and free of burrs.
2. Fit the gaskets dry, without sealant, unless the workshop manual says otherwise.
3. Refit a base gasket of the same thickness as the old one, unless you are deliberately adjusting the squish.
4. Tighten the cylinder head in a criss-cross pattern, in several stages, up to the manufacturer's torque.
5. While it's apart, replace the spark plug and refill the coolant.
6. After break-in, check the torque with the engine cold and make sure there are no leaks.

Why PROX?

Founded in 1975 and based near Amsterdam, ProX specialises in engine and clutch wear parts for off-road bikes. The brand has most of its range made in Japan, by OEM suppliers, for quality on a par with the original parts.

Spare parts and items to plan

• Piston : PROX · WISECO
• Piston rings : VERTEX 590395000001 · VERTEX 590397000003
• Spark plug : NGK 4218 · NGK 3521
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 4-stroke engine oil : LIQUI MOLY 10W40 1 L · MOTUL 10W50

Frequently asked questions

What does the kit contain?
The base gasket and the head gasket.

Should I replace it along with the piston?
Yes: as soon as the cylinder head and cylinder are off, new gaskets go back on. It's the right time to fit a new piston kit and new rings if the engine has some hours on it.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
GAS GAS ECF 450 2015
GAS GAS ECF 450 2014
GAS GAS ECF 450 2013
YAMAHA WRF 450 2015
YAMAHA WRF 450 2014
YAMAHA WRF 450 2013
YAMAHA WRF 450 2012
YAMAHA WRF 450 2011
YAMAHA WRF 450 2010
YAMAHA WRF 450 2009
YAMAHA WRF 450 2008
YAMAHA WRF 450 2007
YAMAHA YFZ 450 2025
YAMAHA YFZ 450 2024
YAMAHA YFZ 450 2023
YAMAHA YFZ 450 2022
YAMAHA YFZ 450 2021
YAMAHA YFZ 450 2020
YAMAHA YFZ 450 2019
YAMAHA YFZ 450 2018
YAMAHA YFZ 450 2017
YAMAHA YFZ 450 2016
YAMAHA YFZ 450 2015
YAMAHA YFZ 450 2014
YAMAHA YFZ 450 2013
YAMAHA YFZ 450 2012
YAMAHA YFZ 450 2011
YAMAHA YFZ 450 2010
YAMAHA YFZ 450 2009
YAMAHA YZF 450 2009
YAMAHA YZF 450 2008
YAMAHA YZF 450 2007
YAMAHA YZF 450 2006