FAQ

What is a MMC material?
How come that the MMC con rod weight less than 50% of its fellow steel con rod?
Compared to Titanium con rods, what are the benefits?
Is it true that the MMC con rod run without a bearing?
What performance gains can I expect?
How much does a MMC con rod cost?
What is the life expectancy of the MMC con rod?
What modifications do I need to do in the engine in order to use the MMC con rod?
What should I think about when assembling a MMC con rod?
What about maintenance?
For what engines are MMC con rods available?

What is a MMC material?
MMC is an abbreviation for Metal Matrix Composites.

A MMC material is a composition of a metal alloy reinforced with ceramics. The material we use in our con rods is Aluminium reinforced with Silicon Carbide particles.

MMC materials combine the toughness of metals and the stiffness and wear resistance of ceramics.

Roughly, the MMC material we use has the stiffness of Titanium and the wear resistance of Steel while having the density of Aluminium. Top

How come that the MMC con rod weight less than 50% of its fellow steel con rod?
MX Composites has over the years found design principles that utilize the material characteristics of MMC materials in a way that results in very light weight designs. The design principles combine the specific stiffness and the tribology properties of MMC.

In conventional materials the specific stiffness (stiffness divided by density) is constant regardless of what material you use, what you gain in stiffness you loose in density. That’s why Steel and Aluminium con rod weigh the same, you need to have thicker cross sections in Aluminium to have it stand up for the same loads as in Steel. However, in MMC material the relation between stiffness and density is changed due to the reinforcements of the ceramic particles. You achieve a much stiffer material without an increase in density. Top

Compared to Titanium con rods, what are the benefits?
Compared to Titanium con rods the weight saving of the MMC con rod is 25%. In addition, the improved heat transfer of MMC leading to less temperature stress on the con rod gives a longer life. Not to forget, the “bearing”-less solution giving a simpler design with less maintenance and since MMC is gentler to other materials there is no need for shims. Top

Is it true that the MMC con rod run without a bearing?
Yes, due to the MMC material and how the con rods is manufactured by the patented High Speed Machining method the con rod itself function as an integrated slide bearing reducing the need for traditional roller bearings and bushings. Studies have shown that MMC has less friction and wear than traditionally used Bronze. Top

What performance gains can I expect?
In short, you will get a more powerful motorcycle that is easier to handle due to less moving mass (less gyroscopic effects) and vibrations in the engine.

Our motocross customers says that riding a motorcycle with a 4-stroke engine equipped with a MMC con rod is like having the best from a 2-stroke small size engine while having the power band from the bigger 4-stroke. The improved dynamics of the engine means a more powerful response especially on lower revs.

Martin Lind explains the benefits and how the MMC con rod help him cut the track times like this:

First of all, the quicker and softer throttle response and the higher revving engine (the rpm limit is increased) gives me a better acceleration in the start and out of the curves.
The lighter crank makes it easier to retard the speed when approaching the curves. In addition the shuttling of the rear wheel is decreased.
Since the lighter crank also makes it easier to manoeuvre the bike I can more easily find the best track in the curve.
When accelerating out of a curve the problem of a wobbling front fork is decreased.
Finally but not least, less vibration give me a more comfortable ride helping me stay focused.
Top

How much does a MMC con rod cost?
The one-piece MMC con rods used in single cylinder 4-stroke engines costs 600 Euro and will give you a performance gain comparable to spending 5 times as much on other tuning parts. Assuming that you use your MMC con rod for 30-40 hours the cost per hour is only 15-20 Euro per hour. That’s probably less than you spend per hour when partying with your friends at a Friday night. We promise you equal fun on the bike when riding with our con rods :) Top

What is the life expectancy of the MMC con rod?
The Husaberg Enduro Factory team have used our MMC con rods for the last five years and some of them have been used for more than 100 hours in racing conditions. Normally they run with the con rods through out the racing season. However, the life of the con rod depends very much on how you rev the engine and under what temperatures it operates. In Supermoto where the average rpm as well as peak rpm of the engine is much higher, the con rod is normally changed together with the piston to be on the safe side.

As long as the MMC con rod is provided with enough fresh oil and runs under the conditions it is designed for you can expect the con rod to service as long as or even longer than its fellow Steel and Titanium con rods. Top

What modifications do I need to do in the engine in order to use the MMC con rod?
The MMC con rod run with the original piston pin and crank pin, but make sure that you use fresh ones with fine surfaces. To have the right balance in the engine and minimised vibrations you need to re-balance your crank by removing mass on the counter weights since the MMC con rod weight less. There are several ways to do this depending on the crank. Normally we reduce the thickness of the crank halves, especially on the inside since we often needs a little bigger clearance between the halves due to slightly thicker rod shaft. Talk to your local engine builder about this operation or contact us.

Some of our customers also remove the balance shaft. The MMC con rod reduces the vibrations to such an extent that the balance shaft is not needed. In some cases you should also remove the restrictor to the roller bearing used in the standard configuration. Top

What should I think about when assembling a MMC con rod?
Make sure that you fill all oil channels to the con rod with fresh oil.
Build up an oil pressure by rotating the crank before you start the engine.
Let the engine warm up properly before revving the engine in order to achieve the right bearing clearance. Read more in our manual.

What about maintenance?
There is no extra maintenance when using MMC con rods. Make sure to maintain the integrity of your engine by following the manufacturer’s service manual. We recommend oil change every 5-10 hours depending on the conditions and that you use synthetic oil for the best performance.

If you use your bike in winter season make sure to make a wide oil viscosity spectrum. Top

For what engines are MMC con rods available?
MX Composites constantly develops MMC con rods for additional engines. We try to keep the list on our website up to date but don’t hesitate to contact us if you don not find your engine in the list. By providing us with some design parameters according to our Design Data Form we design your custom con rod. Top