Aprilia RXV 450/550
By TMX Archives on 4th Dec 06
LAUNCHED amid much hype, interest and speculation only one year ago in the beautiful Sicilian countryside, the unique Aprilia RXV 450 and 550 enduro machines and their sister SXV supermoto-specific mounts were a complete and refreshing break from the norm in the conservative and at times staid world of off-road motorcycle manufacturing.
Continuing in that long Italian tradition of producing highly exotic and individual motorcycles, Aprilia eschewed 'conventional wisdom', made the industry sit-up and take notice, and set pulses racing around the world with the radical and courageous development of the first V-twin, fuel injected four-stroke motor in the sector and its similarly unique chassis design and styling.
The RXVs are about as revolutionary as it comes and to say they have caused a stir is an understatement, so when the invite came in for myself and the boss man, JD, to put the 2007 RXV 450 and 550 through their paces at the official UK launch in the rolling hills outside Ledbury, Herefordshire, last week, the opportunity to be among the first to ride such ground-breaking machinery and see what kind of a job the Aprilia designers have made of producing a V-twin motor for off-road applications was too good an opportunity to refuse and we jumped at the chance.
After a day spent slopping around in the rain, mud and fog of the Herefordshire countryside I was left very much more impressed than I was expecting to be and in no doubt that Aprilia is extremely serious with its off-road intentions and more importantly, very much capable of achieving them with the V-twin design.
There are few things more enticing to a test rider than the sight of a row of gleaming new machines for you to use and abuse and after pulling into the test area in the 5,000 acre grounds of Eastnor Castle to be greeted by a row of gleaming V-twins - 450, 550, production, pre-production, and race kitted with Akrapovic pipes - ready for a good thrashing and crashing and I was more than ready to get out there.
Wheeling away a RXV450 to grab a few static and detail images before the day's ridng started gave me a chance to really have a good look at the finer details of the bike and see just how unique and beautifully engineered the bikes are, well you wouldn't expect anything less from the Italians would you?
A true V-Twin - having just the one crankshaft - the five-speed motor is a work of art and features a 77 degree angle between its two SOHC heads, a dry sump lubrication system with external oil tank, titanium valves, 38mm electronic fuel injectors (40mm on the 550), electric starter and magnesium cases which are claimed to give the perfect balance of maxium power performance, torque and engine response whilst keeping vibration and noise generation to a minimum.
The exhuast system is simply stunning and uniquely exits the rear of the bike via a centrally mounted silencer with twin ports that sits under the rear subframe and mudguard, and combined with the V-twin motor produces an extremely quiet machine that easliy comes in below all noise regulations and puts 450 singles to shame - If only all bikes were this quiet we wouldn't be having half the problems we are with track closures.
In another unique design trait the motor also forms the lower, load bearing half of the bikes chassis and is bolted onto the distinctive frame which blends a trellis type steel structure and the pressed aluminium side struts in a great look of sharp angles and straight lines. The variable section aluminium swingarm extends the unique look of the chassis through to the rear of the bike, but it not just an asethetic add-on, Aprilia feel that this design offers the most rigid rear-end of any enduro machine on the market.
The whole machine is suspended on a Sachs rear unit with cleverly designed horizontal resevior to accomodate the silencer, whilst 45mm Marzocchi Shiver forks take care of things up front, and sharp, angular looking plastics in those distinctive red and black Aprilia colours finish off what is an undeniably lovely looking package.
My only grumble would be that the plastic brace on the front light/ mudguard looks a bit agricultural and spoils the asthetics of the machine bit.
After a good old nosey round the bikes it was definitely time to see what they were capable of out on the going, and I have to be honest I was really very impressed.
Having never ridden a V-twin before I was not sure of what to expect, and I was not overly confident that a twin would be able to perform well off-road, however, not only is it an extremely capable enduro machine that will have broad appeal, from trail riders to racers, incredibly easy to get on with and a hell of a lot of fun to ride, but there is a hell of a lot of potential in the bike, and in V-twin motors, that can still be extracted by Aprilia in the coming years to improve it even further.
I generally like to start with the smallest capacity bike first on a test and work my way up through the range so the RXV450 was my first port of call.
My big major concern when I first swung my leg over the bike was weight. Wheeling the bikes around for pictures they felt like they weighed considerably more than their competition, somewhere up around the 120kg mark I would say, and I was concerned that this would translate into an unresponsive, difficult and tiring bike to ride, but as I snicked it into gear and rode off up the first bit of fire road and onto the tracks my fears were alleviated as the bike feels considerably lighter and very nimble out on the trail.
It obviously does not feel anywhere near as slight as two-stroke, but it measures up well against 450 singles and has distinct advantage over them in that it feels as if the weight is a lot more evenly distributed and the centre of gravity more compact, making it a very well balanced and steady feeling bike. Obviously this has much to do with the chassis design too, and whereas some of 450 singles feel very top-heavy and the weight throws you off your balance quite easily, the RXVs feel extremely well planted indeed thanks to the compact nature of the V-twin with its low centre of gravity and the extra weight is not much of an issue at all.
The result when twinned with the chassis is a superbly well-mannered and very well-handling machine that provides a very forgiving ride. The going was not especially technical, more hare and hounds type going, but it was extremely slick and wet and the RXVs tracked extremely well indeed, really requiring you to give it some very liberal right-hand action before it would even consider getting out of shape, and in rutted sections in particular I found the bikes very stable and impressive.
Engine-wise, the RVXs are very strong and create all the power you could possibly want in any situation you are likely to encounter in enduro situations, and the most pleasant aspect of the engine performance is how well the Aprilia engineers have tuned the V-twin to make it applicable for off-road use.
Riding the bike, the engines produce very smooth, linear power right the way through the rev-range and particularly very-low down in the revs there is an abundance of extremely strong torque that proves very good indeed in very slow, almost trials like going. This is undoubtedly helped by the EFI system which provides the instant throttle response that the competition cannot match and eliminates any coughing or stalling and for big bikes the RXVs are much better than I would have thought at slow speed.
Running up through the gearbox and revs, I found that the bikes will primarily require the bottom three gears in the tighter stuff, and that these are quite closely spaced, but once you get them in fourth and fifth they build power and speed very smoothly. Although they definitely prefer a smooth right-hand and pulling taller gears rather than being thrashed about in second.
If you were a bit aggressive on throttle coming out of a corner I found the back end would break away quite easily and because of the high-revving nature of the V-twin it was not as easy to re-find grip and gather everything back in as it is on a single.
This would be my only real grumble about the bikes' handling or traction, and to be honest once I had figured out how the bikes liked to be ridden and adjusted my style accordingly I didn't have much of a problem.
The engines are very deceptive in their power and build-up speed much quicker than you think, particularly the big 550, and when tagged with the very quiet and flat-sounding exhaust note you can feel that you are not going as fast as you need to be - until you come to a corner that is and realise you are going way too fast to make it.
This took a while to get used to, but again it is not a detrimental character trait and I think trail riders and fans of big, grassy, open going will find this a real positive, especially as it is far less tiring than riding a snappy single all day.
My only other concern with the bikes is that they have quite a serious amount of run-on when you close the throttle right off. I don't know whether this is to avoid stalling the big twin motors, to counteract engine-breaking, or to do with the EFI, but the bikes constantly want to move forward when you roll off the throttle and are always pulling. On the open going this is not really a problem, but when it gets down to the tighter more technical stuff it took a bit of getting used to and I found that quite a lot of rear brake dragging and liberal clutch use was necessary to keep everything in check.
Again this is not an issue if you are looking at using the bike more as a trail riding steed, but may take some getting used to or require tuning out for more serious enduro competitors. That of course is the beauty of programmable ignitions and EFI.
As far as the bikes go, personally I found the big 550 the easiest and most rewarding bike to ride as it was just that bit more torquey and smooth low-down, but the 450 is far from a 'difficult' machine and with a bit more time to play around with a few things it would undoubtedly be much more suited to racing conditions.
I did find the bike preferred to be steered with the power of the rear wheel more than just by turning the 'bars, but once I got used to this I found the bikes cornered extremely well indeed, even in the more technical sections, and quick changes of direction were a doddle, especially on the fast stuff.
All in all, I was very impressed with the RXVs. What I thought might have been big, heavy lumps that produced all the wrong kind of power for enduro riding were in fact impecably well behaved bikes with superb, torquey power and excellent potential. I can't wait to see how Aprilia develops these bikes further and anyone looking for something with character and quality would be well advised to check them out.
Second opinion...
THE chance of a blast off-road on the unique, V-twin-cylinder four-stroke Aprilias was just way too good to miss, writes T+MX Ed John Dickinson.
First off, I do not profess to be an expert enduro rider but on the other hand I have had a thrash on most comparable machinery and wanted to see how the Aprilia stacked-up. Added to which I probably fit the target profile of the fictional average customer, ie a rider with average ability looking for something distinctive but also something that delivers as well as looks good!
And the Aprilia RXV does look good! That technically clever ally/ steel frame, the state-of-the-art V-twin four-stroke engine, plus striking plastics, colours and graphics make for a cool showroom presence.
But our day wasn't about showroom shine, it was about getting down and dirty. And boy was it dirty. And it absolutely hammered down, turning the test venue surface into a surface so slick that you could slide to earth while at a standstill!
On to the bikes. We were lucky in having several variations of the RXV to try. Standard 450, 450 with a pipe and 550 standard. Starting with the obvious, when the flag dropped I bagged a standard 450 and, even with my over-standard 34" inside leg found it was pretty tall. Thumb the electric start and the motor revved immediately into life. It felt responsive, revvy and the exhaust note surprisingly quiet.
Into gear and away. Zipping up through the five-speed box, found second close to first, slightly more of a jump to third and then bigger gaps through fourth and fifth. The engine sort of felt like a cross between a 250 four-stroke single (but with 450 power) and a two-stroke.
The twin obviously has twice the power-pulses of its 450 single cylinder opposition. I had expected it to be possibly too revvy and difficult to find traction with - but I was wrong. There was very good rider feedback between throttle hand and rear wheel and as conditions can't possibly ever be worse than at the test I can honestly say that finding grip was not a problem. It must be awesome on a dry - or even semi-dry - track. We'll try it one day!
The Aprilia is not lightweight - stationary the weight is evident - but once on the move this is genuinely forgotten and the RXV handles a dream. I found it a very easy bike to ride with direction changes just happening automatically. The bike never tried to decide where we were going and some of this rideability must come from the compact wee motor with its different centre-of-gravity compared to a tall single.
The only negative I found was that the engine does run-on when you close the throttle to corner, perhaps a trait of the fuel injection. It means you don't get the benefit (or otherwise) of engine braking. Not a problem on open going but you do have to be careful on nadgery low-gear stuff, especially downhill when you are trying to slow down but the motor is trying to keep you going. The solution is to ease the clutch and adjust speed on the brakes. The benefit of electronic fuel injection (efi) is that the motor is always operating at peak efficiency and the engine will NEVER sneeze or stall as carbureted big singles can.
Given the conditions it was impossible to offer meaningful info on the brakes. The back was fine and helped steady the bike on the slippery going while being honest, the front was a bit sudden. On the other hand it was freezing cold, soaking wet and we were riding on the equivalent of ice. In the dry I guess you could fling yourself over the bars with a silly big handful.
On the suspension front, the forks felt a fraction stiff while the rear felt a tad soft. Having said that, obviously the harder it was worked the better it got and several wheel-deep holes on the test track were soaked up by the front without it even being felt at the handlebars and the back followed through exactly the same. To the rider, the hole simply wasn't there.
A quick switch of bikes and it was off on the Akrapovic exhaust equipped RXV - which comes with its own efi mapping. Believe it or not but this is even quieter than standard. The bike also proved to be smoother (and believe me the standard bike is smooth), offered more torque and to cap it all gave a noticeable top-end hit. A clear case of a winning mod all round with no down-side. This was arguably the easiest of the bikes to ride for good old Joe Average.
Finally, it was onto the 550, and this proved to be just like the tweaked 450, liquid torquey bottom-end power that turned into a wicked, buzzing top-end. This was the ultimate V-twin fun, but one that could obviously get out of hand because it is so damned fast. Awesome and a genuine thrill to ride.
The beauty of efi is of course that it is so easy to tune the power to how you want it. Paul Iddon told us that they were looking at playing with a full 80bhp RXV for factory Supermoto star Christian to play on during the winter - just because they can! Don't fancy that on a slippery grass banking...
Like all bikes, the only way you can possibly know if the RXV is for you is to try one - I would urge you to do just that.
2007 APRILIA RXV 450/550
ENGINE
Type: 77° V twin liquid-cooled, four-valve, single overhead cam four-stroke with rocker operated exhaust valves.
Displacement: 449cc/549cc
Bore x stroke: 76 x 49.5 mm/ 80 x 55mm
Compression ratio: 12.5:1/12:1
Fuel system: Integrated engine management system controlling ignition and fuel injection with 38mm/40mm throttle body.
Ignition: Electronic.
Starting: Electric.
Alternator: 340 W
Lubrication: Dry sump with external oil tank. Separate gearbox lubrication.
Gearbox: Five-speed.
Clutch: Multi-plate in oil bath, cable operated.
Final drive: Chain.
Transmission ratio: 15/48
CHASSIS
Frame Type: Steel perimeter frame with alloy vertical members and box section aluminium swingarm with cast body.
Front suspension: 45mm upside down Marzocchi fork with compression and rebound adjustment.
Rear suspension: Hydraulic Sachs monoshock with compression and rebound adjustment.
BRAKES
Front: Nissin 270mm with floating caliper.
Rear: Nissin 240mm with floating caliper.
WHEELS
Front: 1.60 x 21"
Rear: 2.15 x 18"
DIMENSIONS
Overall length: 2,222mm
Overall width: 800mm
Ground clearance: 396mm
Seat height: 996mm
Wheelbase: 1,495mm
Fuel Capacity: 7.8 litres
Specification: