END OF AN ERA: IS THE TWO-STROKE DEAD IN ROAD RACING? ROAD RACING GOES DOWN THE MOTOCROSS ROAD

July 7, 2010
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The Moriwaki MD250H.

Road racing is changing…fast. Just like in motocross, there are powers-that-be that want to drive a stake into the heart of the venerable 125 two-stroke road racing class.

Case in point: The 125cc World Road Racing Championship is rumored to be replaced by a single-cylinder, 250cc, four-stroke formula starting in 2012. When the FIM kills the 125 class, that will be the end of the two-stroke era (In 2001 all three grand prix classes consisted of two-stroke motorcycles, but their lack of production relevance saw the premier 500cc World Championship replaced by a new 990cc four-stroke MotoGP class in 2002, while the 250cc two-stroke was replaced by 600cc Moto2 four-strokes at the start of this season). The death of the 125 GP class will mean that none of the founding classes from the original 1949 World Championship season still exist.


Look closely and you will see a CRF250 motocross engine tucked into the road race frame.

The 250cc four-stroke class will be called Moto3. The move is fueled by three factors:

(1) Since 125cc two-stroke street bikes aren’t a hot commodity, the 250cc four-stroke ties more closely to the manufacturers product lines.

(2) Unlike the 600cc Moto2 class, the new Moto3 will be open to any engine manufacturer. However, the Moto3 bikes will not be based on existing motocross four-stroke engines (although that would be the cheapest route for aspiring Moto3 teams and racers). According to sources, the Moto3 engines will be specially built with a maximum bore of 81 millimeters, making for much higher-revving short-stroke motors. The current range of 250 motocross engines could produce as much as 45 horsepower in road-race-trim using their current bore and stroke. With a new bore and stroke and purpose-built engine, the 250cc four-strokes would produce closer to 50 horsepower?which is about what a 125cc road racer makes now. Of course, there is additional weight with the four-stroke engine, so it is unlikely that the speeds will increase with the new formula.

(3) As proof of concept, the supporters point to Japan, where there is already a motocross-based, 250cc, four-stroke, single-cylinder class. And, Moriwaki makes a bike called the MD250H that uses a modified CRF250 engine in an alloy beam chassis.The MD250H retails for $11,699. They also have a Suzuki RM-Z250 ready chassis called the MD250S.

Now for something completely different! KTM has a 125cc four-stroke road race bike in the concept stage.

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