VHM Topplocket som vrids efter banan

Tvådelade topplock och utbytbara förbränningsrum i CNC-fräst aluminium för tvåtaktsmotorer inom motocross och enduro.

01Dutch two-stroke specialist

02Two-piece head with exchangeable combustion chamber

03CNC-machined aluminium (billet)

04Set squish and compression by swapping the insert

05Recognisable golden cylinder head

Motocross · Enduro

VHM is a Dutch brand, born from an obsession with racing, that has specialised in one thing: cylinder heads for two-stroke engines. What started with its own carburettor concepts shifted to the cylinder head during the 1990s, and the golden heads soon became a familiar sight in the two-stroke world. The philosophy has not changed since. Every part is machined from a high-grade aluminium blank (billet) on multi-axis CNC, and everything is built around drawing smooth power through the whole rev range.

What sets VHM apart from a cast original head is the two-piece construction. The cylinder head stays on the cylinder, while the combustion chamber itself is formed by an exchangeable insert. By swapping the insert you change volume, squish and compression without touching the rest of the engine, tuning the motor to the track, the weather and the fuel. VHM offers a standard insert for the best all-round power plus higher and lower compression options, and a blank insert for those who want to machine their own squish and volume figures.

The inserts seal against the cylinder head with double o-rings that keep the squish gap precise and stable, and the water passages are shaped to keep the combustion chamber cool under hard load. The range covers the two-strokes from KTM, Husqvarna, GasGas, Beta, Yamaha, Honda, Suzuki and Kawasaki, from the small mini classes up to the 250 and 300. Cylinder heads and inserts are sold separately, so you can start with the head and build out with more combustion chambers as the riding demands.

Frequently asked questions about VHM

Why choose VHM's two-piece head over a cast original head?

The two-piece design is the whole idea. The cylinder head stays put, and the combustion chamber is formed by an exchangeable insert. So you change volume, squish and compression by swapping the insert alone, without touching the rest of the engine. A cast original head is one fixed shape, while VHM lets you set the motor to the track, the weather and the fuel.

What is squish, and why does VHM emphasise it?

Squish is the smallest distance between the piston and the combustion chamber when the piston is at top dead centre. It shapes how the mixture burns, and with it power and the tendency to knock. VHM's inserts seal with double o-rings that keep the squish gap precise and repeatable, and different inserts give different squish and compression. Confirm the right figures for your engine with your dealer or engine builder.

Does VHM suit both motocross and enduro?

Yes, as long as it is a two-stroke engine. The range covers SX and TC motocross machines alongside EXC, XC-W and many enduro models. The exchangeable combustion chamber is an asset for both: from the higher compression for a tight track to a more relaxed setting for enduro, you change the tune through the insert. Confirm the model-specific fit with your dealer.

How do I buy VHM via Knobby?

Knobby sells through dealers, not directly to consumers. Your local dealer orders from the full VHM range and confirms the right cylinder head and insert for your engine, along with availability and current prices. Tell them your bike's make, model and year, and the compression you want, so they can match the correct part number before ordering.

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