Benelli BN251

 

BENELLI BN251

 

Just a few months ago, prior than the Pesaro Court issued its sentence on the “WP against Benelli-Qjian Jiang” case and declared the 105 years old and pretty legendary motorcycle make insolvent, I had the opportunity to test their last released model, the Benelli 251. This is the entry model in a line that has been growing from the day of 2005 when the Qjian Jiang Group acquired Benelli and defined a growth plan in which the Benelli premises in Pesaro were re-configured firstly as a very large R&D department and secondly as a production site for special, top class models.

Since then Benelli Pesaro has been very active in its primary role, far less in the second which is expected to get into gear when the Benelli Three Cylinder engine, born Tornado 900, will be completely revised to express its full, real potential and to power a state of the art top class model.

While the Benelli BN604 600cc four and its derivative BN302 300cc twin were fully conceived, developed and validated at Benelli, the new BN251 was the result of a joint Benelli-Qjian Jiang effort. Specifically in the engine department, where the project engineers took a shortcut and found a sound inspiration in the Kawasaki KLX250 unit.

It does not take much to connect the two singles, starting from the bore and stroke measurements and from the compression ratio, respectively at 72mm by 61.2mm, and 11.2:1. The engine retains the mechanical layout of the unit that inspired the project: chain driven DOHC distribution train, four valve induction, pressed together crankshaft turning on ball and roller bearings, with needle cage at the rod big end.

All in line with the mechanical layout of the Japanese single that inspired the technicians of the Benelli-Qjian Jiang team. Plus liquid cooling, port fuel injection and a countershaft to cancel the vibrations generated by the natural imbalance of primary order typical of the single cylinder engine. Where the Benelli technical staff came brilliantly into play was in the tuning of the engine, and there they marked a substantial success in terms of power, torque and refinement. The engine breathes thru the 37mm throttle body of a perfectly tuned Delphi integrated ignition-injection system.

The Benelli specialists have adopted Delphi integrated systems since long and they have acquired a great competence with them and they put them to very good use on all their latest engines, from the 604 down and this 251 appeared beautifully responsive and rather strong for its size. Power is officially announced at 25 Hp at 9,000RPM with 22Nm peak torque at 7,000RPM, and a very broad torque curve coming in at as low as 3,000RPM, no shudder.

The unit puts to its best possible use a sound thermodynamic section featuring a combustion chamber design that accurately reproduces that of the original Formula 1 Cosworth 3.0 liter DFV V8, with valves (inlet and exhaust valves measuring 27mm and 23mm respectively) set at a 29° included angle. The combustion chamber is compact and to achieve a sound 11.2:1 compression ratio it simply took a flat top piston with shallow valve pockets.

This unit is harnessed by an open cradle frame of well triangulated steel tubing trellis design, and there its acts as a semi-stressed stiffening member of it. Even at first sight the frame appears very sturdy, and the analysis of the steel tubing elements is the final certification. As with all other latest generation Benelli-Qjian Jiang motorcycles, the Benelli specialists resorted to rather large diameter tubing of heavy gauge: 32 millimeter main diagonal tubing, 25 millimeter front down, lower horizontal bracing and upper seat-tank subframe tubing, all gauge 2.5 millimeter, plus 22 millimeter, gauge 2 millimeter, triangulations tubing. Steel tubing is used in the construction of the rear swingarm, with 50 by 25 millimeter, gauge 2 millimeter,  rectangular section main tubular element, further braced by a 25 millimeter, gauge 2.5 millimeter, tubing triangulation that at the top carries the lower mounting of the cantilevered shock absorber of the rear suspension.

This ultra solid construction led to a rather heavy structure, but on most markets of the Far East, where Benelli-Qjian Jiang is most active, motorcycles are largely abused in terms of human and merchandise extra loads and a sturdy frame is an absolute priority over lightness. The frame is fairly large for comfortable two up accommodation, and in fact the wheelbase spans 1397mm. The well conformed and generously padded seat seats the rider 797mm above the ground and the whole bike weighs 142kg, dry.

The chassis is blessed by a modern steering geometry: 24 degrees steering axis rake and 90 millimeter trail, and the long wheelbase ensures a very correctly biased to the front weight distribution. The bike rolls on 110/70-17, front, and 150/60-17, rear, Metzeler Sportec M5 Interact radials. In combination with the cantilever rear suspension, at the front a 41 millimeter male slider telefork offers 120 millimeter wheel travel. Brakes are single disc front and rear. The 280 millimeter stainless steel, daisy style front rotor is heavily slotted for extra lightness and cooling and is teamed to a four piston caliper, while an equally fancy looking 240 millimeter rotor and a two piston caliper take care of the rear braking.

I met the Benelli people with their BN251 in the main square of Predappio, my home town which is about 100km from Pesaro, but offers far more secluded and nicer roads, especially the one that drives from Predappio to Premilcuore, known as la Strada dei Tre Falchi. Being one of the great roads for a perfect motorcycle ride I felt that it was time that I should use it for a test ride.

The BN251 is neatly styled and graphically finished following today’s edgy lines fashion. It comes in white, red and black, but my favor goes to the black, and by a long shot. The seat configuration and the handlebar design induce a very ergonomically correct riding posture that also proved perfectly comfortable for the whole 120 miles of the test ride, up and down my “Three Hawks” road going from my hometown across the Apennines pass to Florence.

The BN251 feels very solid, much more than most economy bikes of this class feel. And at a mere 2,990.00 euros, BN251 is so incredibly “economy” that it costs less than a 50cc scooter, in Italy. The engine starts promptly, idles steadily at a fraction under 1000RPM and is very civilized thanks to a well conceived exhaust system consisting in a medium size resonator tucked under the engine and a large silencer on the right side of the bike. The cable actuated, oilbath clutch requires a very mild effort and the gearbox shifts smoothly.

The little mill revs very willingly, zooming fast to the 10,000RPM redline, with plenty of juice (for the size) from 3,500RPM. Again, more than expected. The chassis is very competent, surefooted, great to ride on that twist road of mine, where straight lines from one corner to the next are less than 500 yards. Hard to hit full top speed, but the BN251 dances fast and brilliantly thru that endless sequence of esses. I can use all six speeds of the gearbox, but their staging is odd, that should be revised and duly adjusted, this engine deserves better gearing.

The brakes are the second weak spot. At first, I was grabbing a handful of front brake and the deceleration was mild at best. Heavy stomping on the rear brake happened to be the cure, but progressively I increased the pressure on the front brake lever and that also proved effective. Sure there was no rick of locking the front brake. Benelli technicians said that they were looking into the problem. The bike is very pleasant, strong and safe, its real power probably soars to 28 Hp and that would be enough to hit 160km/h.

The ride is comfortable, though around the 7,000RPM mark the balancing shaft seems to do less of the good job it does throughout the rest of the revs range. BN251 felt comfortable on the open road as well as thru town (my small hometown, not much). It felt strong, very surefooted, agile and stable, it was from the days I was riding my Ducati 250 Diana around South Carolina that I did not have so much fun on a 250cc bike. 

courtesy of webmatter.de