PROX Top End Gasket Kit (base + head) for KTM EXCF, SXF, XCF 250, GAS GAS ECF, EXF, MCF 250 and HUSQVARNA FC, FE 250 2022-2027

The PROX (embase + culasse) 36.6343 top end gasket kit is designed for KTM EXCF 250, SXF 250, XCF 250, GAS GAS ECF 250, EXF 250, MCF 250 and HUSQVARNA FC 250, FE 250 from 2022 to 2027. 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: 36.6343
• 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 : VERTEX · ATHENA
• Piston rings : VERTEX · PROX
• Spark plug : NGK 3521 · NGK 97225
• 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 250 2025
GAS GAS ECF 250 2024
GAS GAS EXF 250 2025
GAS GAS EXF 250 2024
GAS GAS MCF 250 2026
GAS GAS MCF 250 2025
GAS GAS MCF 250 2024
GAS GAS MCF 250 2023
HUSQVARNA FC 250 2026
HUSQVARNA FC 250 2025
HUSQVARNA FC 250 2024
HUSQVARNA FC 250 2023
HUSQVARNA FC 250 2022
HUSQVARNA FE 250 2026
HUSQVARNA FE 250 2025
HUSQVARNA FE 250 2024
KTM EXCF 250 2027
KTM EXCF 250 2026
KTM EXCF 250 2025
KTM EXCF 250 2024
KTM SXF 250 2027
KTM SXF 250 2026
KTM SXF 250 2025
KTM SXF 250 2024
KTM SXF 250 2023
KTM XCF 250 2025
KTM XCF 250 2024
KTM XCF 250 2023