Moto3 vs MX2: Just dirt bike engines in a Grand Prix chassis?KTM BLOG — KTM BLOG

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KTM 350 SX-F

Moto3 vs MX2: Just bike engines in a Grand chassis?

Same size and but how different is the KTM 250cc Moto3 to its MX2 sibling? KTM Blog grabbed experts and lifted the head to out.

Developing KTM’s M32 engine: Kurt Trieb, Developer, KTM Racing On-Road

The of Moto3 brought with it the end of Grand Prix racing. through the smoke came a new class that adopted an configuration exactly that of an MX2 machine. Arguably the King of the 250 single, KTM has also proved on asphalt in the two seasons of Moto3.

the FIM laid out its rules for Moto3, it that manufacturers like KTM use a motocross engine as a foundation. this rule, KTM’s Moto3 story of two riders and a manufacturer’s crown began a dirt bike. What

KTM Factory engineers adapted one of the single cylinder, MX1 championship (in case you didn’t know, MX1 is a a 450cc class, but KTM produced a 350 to give the benefits of a 250 and 450) and it into one of their 125GP-winning The pictures of Austrian IDM rider Ranseder on this hybrid at the Spanish circuit of Cartagena spread around the world.

but different

“The Moto3 and MX2 produced from KTM are worlds . says Kurt Trieb . the man with Engine Construction for Moto3 engine – originally M32 ( M oto 3 201 2 ) – as he shows us the two very different 250cc single cylinder in the Munderfling-based factory race in Austria.

But first Trieb explains 350cc test mule, seen back in 2010: the test with the 350cc was for a lot of – such as fuel consumption, characteristics, weight – and we learned a But the riders complained so much of They said they be able to finish a race on a with this much


It was clear pretty that the Moto3 engine have to be a completely new design and the chassis surrounding it. “The point is that the engine has to fit the bike concept – the package, mainly of the chassis of course. may sound simple, but there’s a lot to into account” . Trieb

As you can see from the pictures, the Moto3 is quite a lot taller than from the KTM 250 SX-F bike. In maximum ground clearance is for jumps – MotoGP doesn’t Cadwell Park’s ‘Mountain in England.

Trieb continues: main difference between two is that there is a deep and inlet port. The KTM RC250 GP has its behind the headstock, which the engine get more air to increase top end output. The centre of gravity has very important in this but also important was the position of tank, which is a vertical directly behind the inlet This combined with the being quite low makes the looks very tall, but you see it in the bike it fits very of course.”

Different strokes

Moto3 and MX2 use their engines very According to KTM, a Moto3 is always used between and 14,000rpm – the maximum permitted for the class – and a Moto3 rider also be using maximum for about 70% of that time. In there’s hardly chance in a lap for a to get the wires tight for any length of

This difference in style obviously to a vey different requirements the engine, most of all reliability such long durations of revs. Kurt Trieb how they managed that: “On engine we had to design a different system. More oil is needed carries 0.8 litre compared MX2’s 0.3 litre!) and a deep with an additional oil water exchanger accommodates this. The and the clutch are arriving outside the oil, so that, again, is why the looks more tall with MX2 when its out of the bike, but very good in the race

Due to motocross packaging reasons, the on a motocross bike is under the and the fuel tank is in front, decides the appearance of the inlet So an engine will take its not only because of performance, but to fit its ‘package’.

The reason for such a and forward airbox is because is always on full load and a lot of air rushing through, where as is more rolling with the due to constant cornering.


The M32 in 2012 made 54hp and the 250 SX-F made 46hp. of the FIM’s technical requirements for the ‘restricts’ all bikes to a rev ceiling of and controlled with a spec ECU control unit or brain), MX2 has no such limitations and the 250 SX-F rev to 15,000rpm. As the Moto3 bike is by how fast the single piston can a larger bore over its relation is utilised.

Throughout the first Moto3 in 2012, the KTM engine became for having very good top end Offering the riders a wider of power had been an issue for the from the beginning.

Trieb “To provide this we were about a smaller bore, but now we managed to create a quite a powerband even with the big of the engine.”

It´s what´s that counts

The capacities are the and dimensions not so dramatically different. The R’s bore and … is 81mm x compared with the 250 SX-F’s x 52.3mm (basically, take the top off engines and the Moto3 engine has a wider piston), but both a similar piston weight.

big difference”, Trieb proceeds, “Is the crank drive has fully bearings – no roller bearings for the – and has a full countershaft for mass This has been a request of the to reduce vibrations as much as a big effort was made to dramatically this.”

So physically and internally are big differences between these two but there are also very engine design philosophies liked the vertical spilt separate cylinder, finger for the valve train and we’re the piston and conrod design.

“This is an engine design comes from the history and of KTM” . Kurt Trieb With scores of victories in MX2, MX3, Enduro,

Dakar and now Moto3, KTM certainly how to build an engine that is TO RACE!

Inside the KTM Moto3

KTM’s Moto3 engine has designed strictly in accordance the Moto3 regulations, which the following:

Engines may rev to a maximum of rpm

Bore is limited to 81 mm

All motorcycles in regardless of engine, must the same engine


Maximum wide range of and maximum top end power according to the of the category

Durability: one engine last at least 2000km it needs to be rebuilt

The six-speed was designed to last the entire

Engine type: liquid 4-… DOHC single

Bore: 81mm


Displacement: 249.5

Intake dual injector throttle

1 x balancer shaft

Anti clutch

Titanium valves in configuration

KTM in Moto3: 2012 –

2 seasons

24 wins from 34

21 consecutive race wins

2 world titles

2 manufacturer titles

Making a Factory MX2 engine: Florian Ebner, Manager, KTM Racing Off-Road

factory motocross team will race an engine will become the following production bike engine. has always been the way and means the bike you can buy from the showroom is on a very good level. look at any motocross meeting to see how orange bikes there

But to start off with, our factory bike is based on a stock 250 which is at a high level Engine wise, we start on details to raise the performance or it to the riders needs. These changes will alter the characteristics.

Like all tuning, we add components made of more material with higher and with closer tolerances raise this with tuning processes. And then of we test with the factory to see which direction we go with the character.

The delivery or character can be with EFI (electronic fuel mapping, cam timing with and valve timings. A lot of small can still let us adopt the engine to it easier for the riders, such as actuation.

We’re very focused on rideability of the whole and as everyone knows that on an bike it depends on suspension. So things are about suspension and the the engine has on this – from to engine position. It has such an

Rideability is sometimes way more than peak power.

The 250 is a very compact engine. it is definitely obvious is that, to Moto3, we need a lot of ground So it needs to be more compact

We try to centralise the mass in the bike and much easier with engine that is close to the bolts and close to centre of

So the vertical size is very and the engine is cut directly under the The case stops very to the crank, but with a bit of volume for the but not too far down. Partly for ground and because the gearbox and clutch are in oil.

The way an MX rider uses the is very differently to road They will use it around 50 a lap in a race; using it for shifting and to the engine character. So for this we put the clutch in the sump and though we we lose a bit of power by doing it benefits with rideability.”

KTM in 2008 – 2013

6 seasons

130 from 184 races

6 consecutive titles (Tyla Rattray Marvin Musquin 2009/2010, Ken 2011, Jeffrey Herlings

6 consecutive manufacturer world

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