VHM Cylinder Head Insert for TM RACING MX 144 2012-2026

The VHM cylinder head insert is designed for TM RACING MX 144 from 2012 to 2026. On a VHM cylinder head, the combustion chamber is an interchangeable insert (or dome). Changing the insert changes the chamber volume, and therefore the compression ratio, without modifying the head: you adapt the engine to the fuel, the terrain and your riding.

Key features

• Each version shows its three key figures: chamber volume, piston height and squish.
• Change the compression without machining the head, to suit the fuel and the terrain.
• Part number engraved on the insert.
• Fits VHM cylinder heads only.

Specifications

• Brand: VHM
• Manufacturer part numbers: AE32223-068, AE32223-069, AE32223-070
• Available versions: Version 068 (13.20 cc): ref. AE32223-068; Version 069 (13.40 cc): ref. AE32223-069; Version 070 (13.60 cc): ref. AE32223-070
• Engine: 2-stroke

Choosing the right version

Each version is defined by three dimensions: the chamber volume in cm³ (spark plug hole included), the piston height at top dead centre relative to the top of the cylinder (“−0.55”: piston 0.55 mm below the cylinder face) and the squish, the minimum gap between piston and insert. A smaller volume raises compression: more bottom end and mid-range, but a higher-octane fuel may become necessary.

When to change the insert?

• Switch to a different fuel (98 or race fuel with a higher octane rating).
• Engine knocking (pinking) or running hot: compression too high for the fuel.
• You want more torque on tight or sandy terrain.

Change the insert when you change fuel or type of riding, or if the engine pinks. The insert's three dimensions (volume, piston height, squish) must match your engine.

Fitting tips

1. The insert is changed with the cylinder head removed.
2. Check that the actual height of your piston at top dead centre matches the figure given for the insert.
3. Replace the VHM head O-rings every time you take it apart.
4. Check the squish with solder wire before riding.
5. Tighten the head to the recommended torque, in a criss-cross pattern and in several stages, then fit a new spark plug.

Why VHM?

Since 1995, VHM has been designing racing engine parts for two-strokes: cylinder heads with interchangeable inserts, combustion chamber inserts, crankshafts and connecting rods. A specialist brand, used to fine-tune an engine's power without transforming it.

Spare parts and items to plan

• VHM head O-rings : VHM SK33000.VITON · VHM SK33000
• Coolant : MOTUL 1 L · MOTUL 20 L

Frequently asked questions

Will it fit my original cylinder head?
No: VHM inserts only fit VHM cylinder heads.

Which version should I choose?
Choose according to your engine and fuel. Version 068 (13.20 cc): 13.20 cc, piston height -1.65 mm, squish 0.95 mm; Version 069 (13.40 cc): 13.40 cc, piston height -1.65 mm, squish 0.95 mm; Version 070 (13.60 cc): 13.60 cc, piston height -1.65 mm, squish 0.95 mm.

Compatibility

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

Fits:
TM RACING MX 144 2026
TM RACING MX 144 2025
TM RACING MX 144 2024
TM RACING MX 144 2023
TM RACING MX 144 2022
TM RACING MX 144 2021
TM RACING MX 144 2020
TM RACING MX 144 2019
TM RACING MX 144 2018
TM RACING MX 144 2017
TM RACING MX 144 2016
TM RACING MX 144 2015
TM RACING MX 144 2014
TM RACING MX 144 2013
TM RACING MX 144 2012