THE DUNGEY FACTOR: WHAT KTM HAS TO DO TO BUILD A SUPERCROSS BIKE FOR RYAN DUNGEY

August 3, 2011
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Will Dungey and DeCoster be reunited?

There is a lot of talk…generated intially by a Roger DeCoster comment…about Ryan Dungey moving to Team KTM for the 2012 season. As with all silly season rumors, although this one has the signature of “The Man” all over it, you have to take a wait-and-see approach to whether or not it will happen.

BUT IF IT DOES HAPPEN…

But, if it does happen, there will be changes at KTM. What changes? It is rightly assumed that Ryan Dungey will not race the 350SXF. He will want a 450…a fuel-injected, lightweight, ultra-fast, KTM 450SXF. KTM’s European management, most notably Stefan Everts, have been pushing the 350…almost to the point of pushing the 450 out of the product line. That will all change if Dungey goes to KTM.

A fuel-injected, lightweight, ultra-fast, KTM 450SXF is what Ryan will get if he signs the KTM contract. How so? KTM has a fuel-injected 450 engine…already in production. Not only does it have Keihin EFI, but the new engine is six pounds lighter than the old engine and is a totally new design. The new engine is currently used in the 2012 KTM 450EXC, but to be AMA- legal KTM would have two choices:


The new fuel-injected engine is in the enduro bike for 2012…to meet environmental standards in Europe.

(1) Put the fuel-injected engine in the 450SXF chassis for 2012. This entails more than just an engine swap, but could be done. The major issues are only the down rails on the frame and airboot.

(2) Homologate the 450EXC for AMA Supercross and motocross (assuming that the 2013 EXC would get rising rate linkage…which isn’t a sure thing). This would be cheap and effective (since a rising-rate EXC would be identical on most design points and geometry…and where they aren’t identical, AMA rules would allow the race team to change).

HERE ARE THE DETAILS ABOUT DUNGEY’S NEXT ENGINE

450 EFI ENGINE: Compared to the predecessors, the new 450EXC engine generation features a brand-new design. Due to improved packaging, the dimensions of the engine cases are drastically reduced (a major advantage of the smaller cases is the higher ground clearance because the frame tubes can be higher without raising the seat and gas tank). The counterbalancer is no longer in the center of the engine. It has been moved to the side and doubles as the water pump shaft. The engine cases are now die-cast instead of sand-cast (the 450SXF engine is sand cast). This allows the wall thicknesses to be much thinner to save weight?without reducing strength. A special high-strength aluminum alloy is used in the cases to guarantee higher ductility. In order to make the engine more user-friendly, the new generation 450 features one common oil circuit.

The new engine design results in an amazing weight reduction of 2.5 kilograms (just under six pounds) compared to last year’s 450 engine. Most EFI engines typically get heavier because of the magneto system and fuel pump being added, but KTM’s manages to stay in thw eight ballpark?even with a battery and electric starter (plus KTM’s fuel pump is half the size of the units used in Japanese brand machines). The EXC engines will come with kickstarters and electric starters..which means that when the kickstarter, idler gear and shaft are removed, the engine will be even lighter.

COUNTERBALANCER/IMPELLER: Due to improved materials and the creative design, KTM’s engineers managed to reduce the oscillating masses in the 450 engine drastically (15 percent on the 450 engine and 20 percent on the bigger 500EXC engine?actually a 510). This allowed KTM to use a counterbalancer that is over one pound lighter than last year. The counterbalancer and the water pump impeller share the same shaft and are located in a much sleeker side case.

CLUTCH: A new one-piece clutch basket combined with the primary gear is made of high-strength billet steel (look closely at the primary gear). The steel basket, of which a version was used on the KTM 350SXF last year, guarantees improved reliability and, because it is stronger, it can be made smaller to allow the KTM designers to make the engine narrower. For some reason, KTM doesn’t use this clutch on its race bikes, preferring to use Hinson components, but the new KTM Belleville washer clutch, as used on the 2012 450SXF allows for a narrower design…that can be removed through the clutch cover…as opposed to the side cover. The use of the Belleville washer allowed KTM’s designers to add a rubber damping system guaranteeing more transmission reliability. Clutch actuation is still hydraulic (Brembo).


OIL PUMPS: The latest KTM 450EXC engine family features a newly designed oil circuit with two instead of three oil pumps and only one common oil circuit. The pressure pump lubricates the con-rod bearing, balancer shaft, valve train and supplies oil for piston cooling. The suction pump evacuates the crankcase from blow-by and oil, also lubricating the clutch and the transmission.

FUEL INJECTOR: The Keihin electronic fuel injection (EFI) uses a 42mm throttle body in the 2012 450EXC model (the 450SXF is carbureted for 2012). There is optional map selector switch for the ignition timing and EFI software for reprogramming the fuel maps.

CRANKSHAFT: KTM uses an ultra-light connecting rod in the 2012 450 engines (made from a high-grade Pankl steel alloy). The piston is also lighter for 2012?as is the new electric starter motor.

CYLINDER HEAD: on the EFI engine, all ports and the combustion chamber have been redesigned in the single overhead cam cylinder head. The new camshaft actuates four valves via lightweight finger follower-style rocker arms, with high-quality titanium valves on the intake side.


Andrew Short’s bike easily meets the AMA’s 220-pound weight limit…we’d be willing to bet that a Ryan Dungey 450 could also.

WEIGHT: Since KTM doesn’t have a factory 450 Supercross effort they will have to start from scratch…but not really. Andrew Shorts’ KTM 350SXF shares most of its basic design and components with the 450?thus the weight savings parts that worked on Short’s bike would work on a Dungey EFI 450. On the weight front, Andrew Short’s 350SXF weighs 220 pounds (and could be lighter) and Alessi’s AMA National 450SXF is 228 pounds…throw in the lighter engine and you have a 222-pound 450 (with electric start).

Photos: H. Mitterbauer & Erlmoser Marcus

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