VHM Cylinder Head for TM RACING MX 250, MX 300 2015-2025

The VHM AA33154 cylinder head is designed for TM RACING MX 250, MX 300 from 2015 to 2025. A VHM cylinder head is made up of an aluminium body and an interchangeable insert that forms the combustion chamber. By swapping the insert, you set the engine's compression and character to suit the fuel and the terrain, without modifying the head.

Key features

• Two-piece cylinder head: body and interchangeable combustion chamber insert.
• Compression adjustable by swapping the insert, without removing the cylinder.

Specifications

• Brand: VHM
• Manufacturer part number: AA33154
• Engine: 2-stroke

Who is it for?

• Original head damaged by pinking (detonation), cracked or warped.
• You want to match the compression to the fuel, the terrain or a tuned engine.
• You're after a smoother or snappier engine without changing the cylinder.

Good to know

The insert is chosen to suit your engine and your fuel: a smaller chamber volume raises compression, which may call for a higher-octane fuel. Always check the squish when fitting.

Fitting tips

1. Clean the cylinder mating face without scratching it.
2. Fit new O-rings and grease them lightly so they stay in place.
3. Check the squish (gap between piston and head) with solder wire before riding.
4. Tighten the head in a criss-cross pattern, in several stages, to the recommended torque.
5. Fit a new spark plug and refill the coolant.

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

• Top-end gasket kit : VHM SK33000.VITON · VHM SK33000
• Coolant : TWIN AIR 1 L · MOTUL 1 L

Frequently asked questions

Can I change the compression later?
Yes: just swap the VHM insert, without removing the cylinder.

Compatibility

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

Fits:
TM RACING MX 250 2025
TM RACING MX 250 2024
TM RACING MX 250 2023
TM RACING MX 250 2022
TM RACING MX 250 2021
TM RACING MX 250 2020
TM RACING MX 250 2019
TM RACING MX 250 2018
TM RACING MX 250 2017
TM RACING MX 250 2016
TM RACING MX 250 2015
TM RACING MX 300 2025
TM RACING MX 300 2024
TM RACING MX 300 2023
TM RACING MX 300 2022
TM RACING MX 300 2021
TM RACING MX 300 2020
TM RACING MX 300 2019
TM RACING MX 300 2018
TM RACING MX 300 2017
TM RACING MX 300 2016
TM RACING MX 300 2015