The dual exhaust isn't some weight-balancing gimmick, there are actually a pair of cylinders feeding them burnt fumes.
Rumbling V-Twins aren’t just for cruisers anymore. Now you can get that American thunder in a motocross bike. Well, not really. The Aprilia MXV 450 is the newest incarnation of the high-revving 77-degree V-Twin engine, but it doesn’t sound anything like a Harley-Davidson. With enduro (RXV) and supermoto (SXV) models already in production and competing at the highest levels of racing, jumping into the motocross arena was a logical choice. When we first rode the RXV and SXV machines back in August of 2006, we noted that the power delivery felt very well-suited to a motocross application. The aggressive power curve was a bit overwhelming in many off-road situations and we couldn’t wait until Aprilia mated it with matching suspension. That time has come with the new MXV.
Acting as a stressed member of the tubular steel trellis and pressed aluminum chassis, the motor is fed by a pair of programmable 38mm Dell’Orto throttle bodies which are housed inside the airbox located behind the steering head. Two engine firing sequences allow for the standard “Big Bang” and high-performance “Screamer” settings, and the fuel injection system is also adjustable with two different mappings available through a handlebar-mounted button.
Unlike the enduro and SM models, the MXV is devoid of the magic button, instead relying solely on a kickstart lever to get the pistons moving. Structurally, the compact motor is kept light via a combination of alloys. Titanium valves (four per cylinder), aluminum silicon crankcase and magnesium side covers all help shave important ounces. The single overhead cam design for each cylinder houses a very short piston with only a 49.5mm stroke. Bore measures 76mm and the compression ratio is a very high 13:1. Equally as high is the claimed maximum engine speed of 12,500 rpm. Aprilia also says that the under-tail titanium exhaust meets the 94 decibel rule set by the FIM. The twin mufflers are very short, and not tucked away like the Honda CRF250R.
The 50mm Marzocchi fork has proved very popular with European manufacturers. We know from experience that it can be made to work extremely well.
A 50mm Marzocchi fork and Sachs shock have been tailored for MX use, as has the four-speed gearbox with cable-operated clutch which dishes power to a 19-inch rear wheel. Nissin brake calipers squeeze a 270mm wave-style rotor up front and a 240mm disc in the rear. Photos reveal Dunlop 756 lugs on both ends.
The hydroformed aluminum swingarm is much more traditional in design and uses a rising rate linkage to attach the shock. Bodywork is slim and angular, much like the existing Aprilia off-road models. A flush-mount gas cap is recessed at the front of the seat and fills the two-gallon reservoir. Oversized handlebars are without a crossbar and the rider cockpit is much cleaner without the computer found on the RXV/SXV.
Time will tell if we get to see the new Italian motocrosser on American shores, but once it makes a debut, we’ll be knocking on the door to get a test unit. We were mightily impressed with the enduro and supermoto versions two years ago, and the bikes have been making progress and winning races in the time since. If the engineers have finally put it all together, this could be a very competent machine. We haven’t seen weight or power figures yet, but judging from our short amount of seat time, it shouldn’t take much for the MXV to get noticed.
If Aprilia can match the performance of the engine with the chassis and suspension, the MXV 450 might have a fighting chance against the ultra-refined Singles.
Engine: 77-degree V-Twin 4-stroke. Liquid cooled. Single overhead cam with rocker operated exhaust valves, chain timing drive, 4 valve heads, titanium valves.
Fuel: Lead-free petrol
Bore x Stroke: 76 x 49.5mm
Total Displacement: 449 cc
Compression Ratio: 13:1
Fuel System: Integrated engine management system controlling ignition and fuel injection
Throttle Body: 38mm Hard and soft mappings selectable from the handlebars
Ignition: Electronic digital (no battery)
Starting: Kickstart
Alternator: 220 W
Lubrication: Dry sump. Separate gearbox lubrication
Gearbox: 4 speed
Clutch Multi-plate in oil bath, cable operated
Primary Drive: Spur gears. Transmission ratio: 23/65
Final Drive: Chain. Transmission ratio: 14/49
Exhaust System: Titanium. Conforming to FIM standards for 2009
Frame: Cr-Mo steel perimeter frame with aluminum alloy vertical members
Rake: 26.2 degrees. Lightweight rear frame section
Front Suspension: 50mm Marzocchi upside down fork with adjustments for compression and rebound
High-end components like these titanium mufflers prove that Aprilia is willing to put in the effort on this machine. We'll have to wait and see the retail price.
Rear suspension: Pro-Link with Sachs monoshock, adjustable in compression and rebound
Brakes: Front: 270 mm lightweight stainless steel floating disc with Nissin floating caliper. Rear: 240 mm lightweight stainless steel disc with Nissin floating caliper
Wheels: Black anodized aluminum alloy
Front: 1.60 x 21”
Rear: 2.15 x 19"
Tires: Front: Dunlop 80/100-21 51M
Rear: Dunlop 110/90-19 62M
Overall Length: 86.2 in
Overall Width: 32.1 in
Seat Height: 37.8 in
Wheelbase: 59.0 in
Fuel Capacity: 2.0 gal