PROX Complete Engine Gasket Kit for KTM EXC 300, SX 300, GAS GAS EC 300, MC 300 and HUSQVARNA TC 300, TE 300 2023-2025

The PROX 34.6353 complete engine gasket kit is designed for KTM EXC 300, SX 300, HUSQVARNA TC 300, TE 300 and GAS GAS EC 300, MC 300 from 2023 to 2025. When you open up the whole engine, every gasket removed must be replaced. The complete kit brings together the top and bottom end gaskets under one part number: cylinder head, base, crankcases, covers and exhaust, depending on the model.

Key features

• All the gaskets for a complete engine rebuild.
• Materials chosen according to location, from multi-layer steel to synthetic fibre (ProX).
• Designed to work with ProX pistons and connecting rods as well as with original parts.

Specifications

• Brand: PROX
• Manufacturer part number: 34.6353
• Weight: 170 g
• Engine: 2-stroke

When to replace it?

• Oil seeping at the crankcase or cover joints.
• Coolant or oil leak after the engine has been apart.
• Gaskets hardened, torn or stuck to the parts on disassembly.

During a complete engine rebuild (connecting rod, crankshaft bearings, gearbox) or whenever the crankcases are split.

Fitting tips

1. Clean all the gasket faces without scratching them and remove any remains of old gaskets.
2. Fit the gaskets dry, except where the workshop manual specifies sealant.
3. Replace the O-rings at the same time: a crushed O-ring can't be reused.
4. With the cases split, also replace the crankshaft bearings and oil seals and check the gearbox bearings.
5. Tighten the crankcases and covers in a criss-cross pattern to the manufacturer's torque, then fill up with oil and coolant.

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

• Crankshaft bearings and seals : ALL BALLS
• Engine oil seals : PROX · INNTECK
• Gearbox bearings : HOT RODS TBK0019 · HOT RODS HR00088
• 2-stroke oil : LIQUI MOLY 1 L 3065 · LIQUI MOLY 1 L 3063
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• Spark plug : NGK 6664 · NGK 97225

Frequently asked questions

Are the oil seals included?
The manufacturer does not say for this part number: compare with your original seals.

What does the kit contain?
The top-end and bottom-end gaskets needed for a complete engine rebuild. ProX doesn't publish a part-by-part list: compare with your original gaskets if in doubt.

Compatibility

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

Fits:
GAS GAS EC 300 2025
GAS GAS EC 300 2024
GAS GAS MC 300 2025
HUSQVARNA TC 300 2025
HUSQVARNA TE 300 2025
HUSQVARNA TE 300 2024
KTM EXC 300 2025
KTM EXC 300 2024
KTM SX 300 2025
KTM SX 300 2024
KTM SX 300 2023