VHM Cylinder Head for TM RACING MX 85 1999-2026

The VHM AA33070 cylinder head is designed for TM RACING MX 85 from 1999 to 2026. The cylinder head closes off the top of the cylinder and forms the combustion chamber. On a two-piece VHM head, the chamber is a machined insert that can be swapped in a few minutes to adapt the engine's compression.

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: AA33070
• 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?

Founded in 1995, VHM specialises in racing engine parts for motocross, road racing and karting. The brand started out with cylinder heads featuring interchangeable combustion chambers, which became its speciality, and then developed crankshafts, connecting rods and gasket kits.

Spare parts and items to plan

• Top-end gasket kit : VHM SK33000.VITON · VHM SK33000
• Spark plug : NGK
• Coolant : MOTUL 1 L · MOTUL 20 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 85 2026
TM RACING MX 85 2025
TM RACING MX 85 2024
TM RACING MX 85 2023
TM RACING MX 85 2022
TM RACING MX 85 2021
TM RACING MX 85 2020
TM RACING MX 85 2019
TM RACING MX 85 2018
TM RACING MX 85 2017
TM RACING MX 85 2016
TM RACING MX 85 2015
TM RACING MX 85 2014
TM RACING MX 85 2013
TM RACING MX 85 2012
TM RACING MX 85 2011
TM RACING MX 85 2010
TM RACING MX 85 2009
TM RACING MX 85 2008
TM RACING MX 85 2007
TM RACING MX 85 2006
TM RACING MX 85 2005
TM RACING MX 85 2004
TM RACING MX 85 2003
TM RACING MX 85 2002
TM RACING MX 85 2001
TM RACING MX 85 2000
TM RACING MX 85 1999