Aprilia Rxv 4.5
APRILIA RXV 4.5
Will your next dirtbike be a V-Twin?
RYAN DUDEK
APRILIA IS NOT A renowned brand among off-road enthusiasts, but that will quickly change when the company’s 450cc V-Twin hits American soil. Although banned from AMA Pro racing before it even arrives here, an RXV enduro/dual-sport version is set to make a showing against the current single-cylinder class leaders. CW was lucky enough to throw a leg over not one, but five versions of the bike-a pre-production (and minimally street-legal) RXV 4.5 stateside followed by the Aprilia world press launch in Italy, where I rode dirt and supermoto versions of the 450 and punchedout 550.
Though Aprilia does not yet have an American off-road following, building a successful dirtbike is nothing new for the Italian company. Off-road involvement dates back to 1970 with the Scarabeo motocross bike, includes rally racing in the ’80s and continues to the present dabbling with a variety of models, including enduro, trials and adventure bikes. Now come the 450/550s.
CW RIDING IMPRESSION
Aprilia employees pride themselves on innovation, design and technology. The RXV exemplifies this pride. My first glance at the gleaming Twin had me wondering about the bodywork, or lack thereof. It is weird to see a dirtbike without side numberplates-to me, it looks like it’s missing vital parts-but the bike’s abbreviated plastic exposes a nifty central exhaust system that doubles as a mudguard. The Aprilia team paid extra-close attention to detail, with clean looks throughout, including a digital instrument panel and sleek LED taillight.
Aprilia developed a perimeter-style frame for the RXV that features a latticework of tubular steel secured to pressedaluminum sideplates. The engine and the frame together make a single unit assisting each other with the load-bearing duties. A Marzocchi fork (45mm on the RXV; 48mm, SXV) and Sachs shock anchor the chassis.
Power-wise, there’s an abundance of juice from the 77degree V-Twin; the claim is 60 horsepower for the 4.5, and a whopping 70 for the 5.5. Each compact, four-valve, sohc cylinder is fuel-injected via 38mm (40mm on the 550) throttle bodies. The dry-sump lubrication system utilizes an external oil tank; that way, gearbox and engine oil are kept separate to eliminate contamination between the two.
In pre-production form, the electric-start-only Twin struggled to fire when cold, a problem fixed on production machines by adding a choke-like fast-idle mechanism. On press day in Sicily, the bikes lit promptly with an easy touch of the starter. When the bikes were cold, however, EFI mapping was a smidge off and the engines behaved much like carbureted Singles, exhibiting a few sputters and coughs until up to temperature.
Fully warmed, the RXV was glitch-less and rumbled with a low and wholesome noise that no other 450cc dirtbike makes. A quick snap of the throttle revved the engine rapidly, resulting in a sound more like that of a sportbike than an enduro. The motor gave me the giggles.
Short-legged riders will not be so happy with the seat height, a rather tall 39.2 inches. Though wheelbase at 58.8 inches is on par with the one-lung competition, the whole bike feels larger than other 450 enduros. Claimed dry weight, at 268 pounds, is close to the Singles, so maybe it’s the funky-shaped gas tank that plays a part in the large feeling.
The first thing I noticed when riding was throttle responseit was borderline too responsive. In fact, it was hard to hold a steady wheelie as any slight movement of the wrist would either boost the power or chop it. Secondly, I was amazed at how agile the bike was, bulky feeling or not. With daylight dwindling during my prototype ride in SoCal, I really had the hammer down on backroads to get home before darkness overpowered our aftermarket headlight. Then, the 450’s responsive power was great at speed-lean it over in the corners, get on the gas early for the exits. The bike would simply pull and straighten out in the perfect spot every time. I felt like I was one with the road, everything in perfect unison. This made me even more excited to ride the production model.
What better place than Sicily-moist dirt, rocky hills, adventure around every corner. I rode the RXV 450 first followed by the 550, which differs in bore/stroke and the bigger throttle bodies. Both bikes felt nimble and well-balanced. Again, power was pretty aggressive for trail work and hard to tame when traction was minimal. On anything really slippery, forget it, the rear wheel just spun. The bike revved fast and put that quickness right to the rear knobby; it worked best in higher-speed conditions and would be awesome on a sand track. Hopefully, we will soon see this motor in a motocross chassis. As for the ban, it only applies to Pro racing, and after the whole Ricky Carmichael fuel/points/penalty fiasco, maybe the AMA will flip-flop about the Twin, too. The RXV 550 felt similar to the 450 in all areas except speed. If you want speed, go with the 550, which is old-style 500cc two-stroke fast.
On to the SXV, the supermoto version, a bike already proven by rider Jerome Giraudo winning the Supermotard S2 World Championship against the Big Five’s (Japan plus KTM) 450cc Singles. Maybe that had something to do with the AMA ban...? The SXV differs from the RXV in a number of ways. Tires and brakes are obvious; harder to tell is the wider swingarm, different fuel management, revised gear ratios and extended countershaft that moves the sprocket out, making room for the larger tire.
We had four sessions of 10 minutes each on the SXVs, plenty of time to scare myself witless. I’m still a learner when it comes to supermoto. Nonetheless, everything worked near-perfectly on the bikes—one slight bother on both the 550 and 450 was the lack of a slipper clutch, as both chattered the rear wheel badly backing it into turns. Or maybe it was just me.
Overall, Aprilia has a Good Thing going with this new family of V-Twins. The off-road and supermoto versions will be here this summer, priced at $8199 and $8399, respectively, for the 450s.
Unfortunately, Aprilia missed the homologation period to get the bikes DOT-certified as street-legal in the U.S. It may be 2007 before we see those as early-release ’08s. Of course, by that time, there may be a 550 repli-racer version, and rumors suggest that joining two of the motors together to form a liter-class V-Four is a possibility.
Well, what did you expect? Aprilia makes sportbikes, too, ya know.
