KTM Four-Stroke Moto3 Roadracer - Racing

Austrian manufacturer KTM showed its Moto3 roadrace bike and engine, looking the part with smoothly shaped everything. The eye immediately finds a trellis frame, a long-taper megaphone and curious carbon-fiber rim and spoke fairings on its front wheel.

Moto3 is Dorna’s replacement for the 125cc class that has been a part of Grand Prix racing since 1949. Rules for 2012 require a single-cylinder four-stroke of 250cc and a maximum bore of 81mm (which implies a stroke of 48.5mm). A maximum of four valves must be driven by a chain cam drive (in photos, you can see its tensioner behind the cylinder, indicating forward crankshaft rotation), and neither variable valve timing nor variable-length exhaust is permitted. A spec ECU must be used without modification. Basic engine structure and the piston must be of aluminum alloy, and the connecting rod must be either steel or titanium. An engine maker must provide enough engines and parts to support 15 riders, and engine price may not exceed 12,000 Euros (about $16K).

KTM’s liquid-cooled engine can only be called “columnar,” as it stretches a great height from its deeply triangular oil sump to the top of its very narrow-valve-angle head. My reaction upon seeing the first photos was, “Holy cow, it looks like a two-stroke motocrosser with a four-stroke top end atop its head!” Engine weight is stated as 55 pounds. Two separate exhaust pipes emerge from the front of the head and turn abruptly downward, suggesting an intended engine position close to the front wheel. Intake downdraft angle appears to be about 45 degrees.

Honda’s new NSF250R Moto3 engine gives a claimed 48 hp at 13,000 rpm, a power level which makes it equal to one cylinder of a BMW S1000RR—filling its cylinder quite well but not yet making full use of the permitted rpm redline. Racing will sort that out quickly, and rear-wheel horsepower of top machines should be close to 50. KTM has so far made no statements about rpm, power or torque range. And why should they? Like NASCAR, Dorna has essentially taken design out of the hands of the engineers and printed it in its rulebook.