DOMA Expansion Chamber for YAMAHA YZ 65 2018-2026

The DOMA 100436 expansion chamber is designed for YAMAHA YZ 65 from 2018 to 2026. The expansion chamber is what gives a two-stroke engine its character. Well designed, it improves cylinder filling; dented by stones or crashes, it costs power.

Key features

• Handmade in Calais, France.
• 1 mm raw steel, laser-cut parts, pressed and then welded on a jig.
• Developed on the dyno and on the track.
• Works with the stock silencer or a Doma silencer.

Specifications

• Brand: DOMA
• Manufacturer part number: 100436
• Engine: 2-stroke

Who is it for?

• Stock pipe dented or cracked after a crash.
• Looking for more response and more power.

Good to know

Competition use only: this pipe is not road-legal.

Fitting tips

1. Reuse the stock connecting O-rings if they're in good condition (not included), or fit a new exhaust gasket.
2. Offer up the pipe without forcing it, fit all the mounts, then tighten.
3. Warm up the engine and check for leaks at the joints.
4. Check the colour of the spark plug after the first few rides.

Why DOMA?

Doma Racing has been handcrafting its two-stroke exhausts in its workshop in Calais, France, since 1992. The brand won the 125 world title in 2000 with Grant Langston and supplies original equipment for certain KTM models.

Spare parts and items to plan

• Exhaust gasket : MOOSE · ATHENA
• Spark plug : NGK

Frequently asked questions

Do I need to change the silencer?
No: the pipe works with the stock silencer or a Doma silencer.

Is it road-legal?
No: for competition use on closed circuits only.

Compatibility

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

Fits:
YAMAHA YZ 65 2026
YAMAHA YZ 65 2025
YAMAHA YZ 65 2024
YAMAHA YZ 65 2023
YAMAHA YZ 65 2022
YAMAHA YZ 65 2021
YAMAHA YZ 65 2020
YAMAHA YZ 65 2019
YAMAHA YZ 65 2018