VHM Custom Parts

Custom Inserts

Besides our standard, optional and blind inserts, we also offer the possibility to produce a custom insert. Thereby we machine the insert according to your requested specifications. When ordering a custom insert, we need to know the following desired values from you: volume, squish, piston height, piston radius, combustion chamber shape and amount.

• Your insert specifications
• VHM high quality
• Already possible from 1 piece

Note that we always need to review custom project requests and are not always able to produce, please keep that in mind.

Insert shapes

Order form - how to order a custom insert?

Want to order a custom insert? Please fill in the below form and make sure to fill in all the requested info. You can mail this form to your VHM dealer.

Compression ratio

The compression ratio can be adjusted, by increasing or decreasing the volume of the combustion chamber. What compression you need, depends on the track and weather conditions.

A higher compression ratio, which means less volume, will give the engine more low and middle range torque. This will improve the acceleration and increases torque feeling when accelerating. However, this compromises top speed and the insert is more sensitive to detonation.

A Lower the compression ratio, which means more volume, will result in better overrevolution characteristics. We advise MX drivers to use inserts with a bigger volume on fast tracks to improve topspeed. However, this can compromise it's bottom power.

Custom Crankshafts

Besides our VHM crankshafts and OEM crankshaft modifications, we can also produce a custom crankshaft batch for you. Need a crankshaft for a big bore cylinder? Or need a crankshaft for a rare engine? Ask us for the possibilities! Minimum quantity for a custom crankshaft batch is 10 pieces.

• Your crankshaft specifications
• VHM high quality
• Possible from 10 pieces

Note that we always need to review custom project requests and are not always able to produce, please keep that in mind.

How does it work?
First of all, we work with your information and then calculate the balance, inertia and weight of your OEM crankshaft. We also give advice for the design of the new crankshaft. After 2D production drawings, we produce the crank web out of special material. The crank web gets a heat treatment with the specified hardness. After the heat treatment, the crankshafts are grinded to exact and precise dimensions. Finally, we assemble the crank web with the connecting rod kit together with special tools. In the end, each crankshaft will be aligned with high accuracy. Contact us for prices and specific information.

Our experience and previous work
In the past, we've already produced many custom crankshafts for the highest levels of motorsport. We've made custom roadrace crankshafts for a Yamaha TZ125 and a Honda RS125 ND4 1984 - 1986 engine, and also for several teams like CRP Racing, driving with a Honda RS125, for Derbi GP125 (Jorge Lorenzo, when riding for Derbi Racing, has won several GP's in 2003 and 2004 using our cylinder head and crankshaft) and for Malaguti GP125 and Ajo Motorsport.

We've also made several custom motocross crankshafts. For example for Jan de Groot from Team Kawasaki Europe (Mickaël Maschio, world champion in 2002, used our cranskhaft in his Kawasaki KX125). In 2011 we produced custom made crankshafts for Pro Circuit for their KX250F 4 stroke racing bikes. Recently we produced custom stroker crankshafts KTM 85SX (112cc) 2018 for Gizmo Mods. With a big bore of 52 mm and a stroke of +3.75 these cranks can be used for 112cc.

We even created a special VHM crankshaft for a radio control (RC) 1:6 scale off road car, with which Kay Koops became European champion in 2011.

Custom connecting rods

Need a special connecting rod? For example a longer rod, or a conrod for a rare engine? Contact us for the possibilities. Minimum order quantity for a custom conrod is 10 pieces.

• Your connecting rod specifications
• VHM high quality
• Possible from 10 pieces

Note that we always need to review custom project requests and are not always able to produce, please keep that in mind.

Our experience and previous work
We have have produced custom long +2mm conrods for KTM 85SX and 125SX engines for Hardcore Racing Ltd.

Custom pistons

We do sometimes make custom pistons. We have a minimum order quantity of 50 pieces, but it also depends on the specifications of the piston. Our focus lies on the piston diameter range of Ø40 - Ø60mm with a piston pin Ø12/Ø13/Ø14/Ø15/Ø16/Ø18. If you would like to request for a custom piston project, you can contact us. Please mention the specifications of the piston (diameter & length of the piston, diameter piston pin, weight of the piston, and so on). Then we can assess the request and get in touch with you about it.

• Your piston specifications
• VHM quality
• Possible from 50 pieces and potential repetitive orders

Note that we always need to review custom project requests and are not always able to produce, please keep that in mind.

Our experience and previous work
So far we've made custom pistons for a BRC superkart engine, Zenoah RC, Vespa GS150, 80cc and 125cc Zundapp, Bidalot, Puch and KTM engines. We can also make a custom batch of an existing VHM piston, but then with slightly different specifications as requested.

Other custom projects

Looking for another custom part for your engines? Get in touch and ask for the possibilities! Customers can rely on our experience and skills for a complete design, prototype and manufacturing to a special engine component. At the pictures on the right you can see some projects we've produced in the past; a clutch basket, a special customer-oriented measure tool and a triple clamp.

Note that we always need to review custom project requests and are not always able to produce, please keep that in mind.