Ducati 450 R/t
CYCLE WORLD ROAD TEST
DUCATI 450 R/T
Meet The Desmo-Rooter: A Set-It-Up-The-Way-You-Like-It Charger.
IS THERE ANYBODY out there who appreciates the virtues of a 500 class four-stroke Single any more? (Echo.) Hmmm, not many left, maybe. Too bad people have to be so damn serious about specialized dirt machinery, light weight and all that stuff.
For those of us who still appreciate the vibrant throb of a Roto-Rooter, its single power pulse traction, and torque from practically zero rpm, there are only two machines. The BSA 500 and the Desmo Ducati 450 R/T. BSA offers its Single in three models: motocross, dual purpose and roadster. The Italian Ducati goes a slightly different route, offering you a sparse basic package with a lighting kit, then leaving you to puzzle out how to make the package fit your needs.
The 450 has that neither-here-nor-there quality of nonspecialization, the one that says, “Set me up the way you like me.” As delivered, it works best as a woods bike, but begs modification for desert, fire road riding, maybe even Sportsman TT racing. Given a loving and clever owner, a RotoRooter can be made to do anything. And it sounds and feels so good!
The Ducati R/T is not dual purpose in the strictest sense, as it is not completely street legal in all states when its lighting kit is installed. The kit, consisting of a headlight, taillight, wiring and handlebar switches, does conform, however, to most federal licensing standards. The notable exceptions here are lack of a device to activate the brake light, and lack of horn and muflier. The kit does provide the basics though; all that is needed to complete the package is a little extra work and a few inexpensive parts.
The Ducati R/T’s biggest drawing card is its single overhead cam engine with desmodromic valve gear. A desmodromic valve system is one that mechanically opens as well as closes the valves, as opposed to the conventional system in which valves are mechanically opened by a camshaft/lifter arrangement and then closed by a strong spring. Desmo valves have heen considered advantageous because valve floating at high rpm is completely eliminated, thus insuring greater reliability. Another less obvious advantage is that less internal friction is created in the valve mechanism, yielding increased power output over a similarly tuned engine with a conventional valve train.
While use of a desmodromic valve system is quite rare, it is certainly not a new idea, and it has heen proven to be quite reliable in competition. In 1955, designer Fabio Taglioni completed his first desmodromic engine, a 125-cc Single. A year later, Degli Antoni piloted this 125 to victory in the Swedish Grand Prix. What's more, only a crash at the Ulster GP the following year kept the Desmo 125 from defeating MV for the 125cc world title.
In the racing version, valves were closed mechanically to within 0.012 in. of their seats. It was left to inertia and compression pressure to seat the valves. The engine worked super at high rpm, but idled erratically, due to improper seating of the valves. Kick starting was impossible because the engine had little or no compression at cranking speed.
Perhaps this is why Ducati did not use the desmodromic valve principle on their production bikes until 1968. The 450 Desmo is a more simple design than the racer was, but, like the racer, it is completely reliable. In the 450, a single overhead cam with four lobes is driven by a bevel gear on the right side of the engine. Followers mechanically open and close the valves, which are now seated by springs. Hence, the R/T starts easily and runs well at low rpm.
Carburetion is handled by a 29-mm Dellorto concentric and, as expected, the power band is very broad. In fact, the 450 pulls well from a little over idle to its 7000-rpm power peak. The 38 blip produced is delivered to a close-ratio, five-speed transmission by helical cut primary gears. Shifting is positive. Internal ratios are well spaced, but overall gearing is too low to take advantage of the engine’s broad powerband.
An ignition switch is not fitted and the engine is stopped by a compression release. The release is mounted in the side on the cylinder barrel just behind the camshaft bevel gear, but it sticks out too lar to be protected by the engine. If the bike is laid down on the right side during a crash, there is a strong possibility that the release and its cable will be damaged. Fitting a longer cable and rerouting it behind the frame tube just to the rear of the release would help.
As a trail mount, the Ducati R/T is superb. It is particularly suitable for Northern California or Fast Coast terrain where trees, gullies, and mud bogs keep the speed down. Steering is quick and light, allowing excellent control at slow speeds. Bars, too, are comfortable when the rider is standing, and they are sufficiently wide for good leverage. Ground clearance is a generous 9 in., and rocks and logs can be easily cleared. And, while the ultra low gearing is useless on the street, or in high speed, off-road situations, it is handy when riding in close quarters. Quite simply, the R/T is a climber. Hills present no problem—either going up or coming down. Brakes are seldom needed, due to the engine’s good braking characteristics, and, of course, the bike’s low gearing.
Unfortunately, all of these characteristics (low gearing, high > ground clearance, quick steering) which make the R/T excel in the woods, work against the bike for high speed, off-road riding.
Aided by a quarter-turn throttle and low gearing, the engine reacts quite rapidly and doesn’t seem to possess much flywheel. VVheelspin is excessive-much like a powerful Twin. For high speed work, the bars are too high (the R/T also has a high steering head) and are swept back, forcing the rider to the rear on a machine that has a light front end. The R/T slides easily, but these slides are difficult to control, unless you sit forward against the fuel tank. Steering is ultra rapid. On relatively straight sections of fire road or in sand washes, the R/T twitches from side to side, sometimes to an alarming degree if the surface is irregular.
High speed stability and slower steering, however, can be achieved by either modifying the triple clamps or the frame itself to increase front fork rake. Both methods have proven successful.
While frame geometry is completely different from the 450 Desmo Roadster, design is similar in that the engine is used as a structural member of the frame in both applications. Three toptubes are incorporated in the unusual design. The center toptube passes from the top of the steering head all the way back to the upper shock absorber mount. At this point, a hoop to support the rear fender is bolted on. The single downtube terminates at, and is bolted to, the engine. Two parallel tubes which pass downward to the swinging arm pivot from the aft toptube crossbrace support the engine at the rear. The swinging arm passes inboard of the frame tubes, as is common practice. The footpegs, made of 3/4-in. OD bar stock with a plate welded on top, are of the folding, spring-loaded variety.
In an effort to make the riding characteristics as adjustable as possible, four upper shock mounting points are provided instead of just one. The position most rearward, which makes the shocks practically vertical, raises the rear of the bike slightly and transfers weight forward. Moving the upper mount forward angles the shocks more. This gives the swinging arm increased leverage and softens the ride.
A friction type steering damper which passes through the steering head is particularly useful on the Ducati, as the steering is extremely quick. A fork stop prevents the forks from damaging the gas tank. The unit consists of a tab welded to the front downtube which contacts stops on the triple clamp. It’s not nearly strong enough, though, and one crash will bend it considerably.
Of interest is the rear wheel adjusting mechanism. It consists of a cam-type washer shaped similar to a French curve. I he axle hole is offset. When the washer is turned counterclockwise, it rotates against a tab welded to the lower shock mount, and moves the wheel farther back in the swinging arm. The washer has been reference-notched to allow easy visual alignment of the rear wheel.
The front forks are another new item. Manufactured by Marzocchi in Italy, they are of Ceriani design and have 7 in. of travel. The spring rate is well suited to the R/T Ducati and damping is variable by substituting oils of varying viscosity. The ride is very soft, certainly a plus factor on long rides in the boonies.
The rear shock absorbers don’t work nearly as well. When the rear brake was applied on downhills, the wheel hopped, indicating that they have inadequate rebound damping. Substituting a set of Konis cured this completely.
Both front and rear brakes are full width units, quite large for an off-road machine. Lever pressure is light, but tends to be a bit grabby and causes the wheels to lock up easily, especially on downhills. These units should be easier to use, however, when the linings become worn a bit.
Knobby patterned tires, a 4.00-18 at the rear and a 3.00-21 in front, are mounted on Borrani units. They are of Akront design, but unlike Akront rims, they bend easily. Rim locks, a must on a torquer like the Ducati, are also absent. Two locks should be installed in the rear rim and one in the front to prevent spinning a tube.
Controls are first rate. The levers are soft, have a good feel, and bend rather than break. Rubber covers connect the cable housings to the lever assemblies and, like Magura levers, there is a large knurled wheel that allows the cables to be adjusted while the bike is being ridden. A handlebar-mounted choke is bolted through the right lever. The compression release on the left can be reached while still holding onto the handlebar grip.
The R/T’s body components and stylized fenders are made of fiberglass, but not of the flexible variety. Consequently, the fenders break all too easily, even though they are rubbermounted. The high-mounted front fender presents no clearance problems, but the same cannot be said of the rear unit, which isn’t wide enough to cover the tire and rubs frequently. Ducati dealers recommend substituting yellow Preston Petty unbreakable fenders for the stock components; this would solve both the clearance and breakage problems.
Another potential problem is the fuel tank. After 100 miles or so of trail riding, stress fractures appeared in the gel coat. These were probably caused by vibration, and careful mounting of the tank may or may not cure this. Two fuel taps should provide good fuel delivery, even when the tank is low. The petcocks, however, are mounted up in between the frame tubes quite close to the head. They are difficult to get to when the engine is cold, and are impossible to reach without burning a hand when the engine is warm. While shutting off the fuel taps isn’t usually necessary on a four-stroke, it would have been better to mount the taps elsewhere.
Unlike most Italian bikes, the seat is soft, wide, and provides good support for the rider. It’s long enough for packing double too; all that’s needed are a set of passenger pegs.
Fiberglass side panel/number plates conceal the aircleaner, which is centrally mounted just in front of the rear fender. The 8.5-in. diameter by 2.5-in.-thick unit houses a paper element that does a good job of Filtering as long as it is dry. The only thing wrong with this aircleaner is that it is difficult to service in its present location. The backing plate is held on by a single wingnut which is easily removed, but the bottle for the chain oiler and the close proximity of a portion of the rear fender mount make it impossible to get the cover off without removing the bottom mounting bolt and bending the aircleaner forward slightly. At best, it is both difficult and inconvenient.
The chain oiler consists of a plastic bottle, with a capacity of approximately a pint, mounted to a frame tube just above the chain. A valve at the bottom of the bottle controls the flow of oil. The valve can be shut off completely if oil is not desired, or the rate of flow can be adjusted as necessary.
For a new design, the R/T Desmo Ducati shows much potential. As delivered, its soft ride and broad powerband will endear it to trail riders who spend long hours in the saddle. Add a speedometer and spark arrester, then “dial in” the handling, and the R/T should be competitive in enduros as well. The possibilities are endless, for this is a machine that can be easily modified for satisfying results in a variety of uses. [Ö]
DUCATI 450 R/T
$1189
