That the Gilera RC 600 It was a good bike Nobody doubted. The victory in the previous edition and eighth place overall (only sophisticated prototypes in front of him), constituted an excellent calling card for the Thumper Arcore. The Gilera and Medardo have gone beyond expectations with a performance very similar to that of the prototypes. With only 560 cubic centimetres, the RC has been successful on many occasions to keep keep strong rhythm imposed by two cylinders and Medardo has also won the stage of 5 January from Tumu Ghat, the “Special” longer than the Paris-Dakar.
Not all was well for Gilera: tears of the rear tank fuel overflow and poorly secured, broken starter post on the bike Mandelli who requested the change of engine (automatic change of category) and an experimental power that made a tantrum when starting engines, Apart from a shock absorber destroyed by Medardo. The Gilera are satisfied also because they feel that the Dakar is a great help for series production.
Ing. Maden, Technical Manager, is absolutely convinced of the validity of the formula Silhouette of Dakar. The fact that pushed us to compete in the marathon in Africa and particularly in this category, is the specific regulation. Run the entire Dakar without changing engine and chassis is a highly reliable message to the audience. An engine that can withstand more than 10,000 kilometers of continuous torture without problems, is a guarantee for a series.
In category Silhouette engine and chassis are standard while the rest can be changed. To improve cooling we used larger radiators with upper heat exchange 30%. The control unit until halfway through the race was different from that fitted to the RC 600; an ignition that gave very few advantages in terms of power but that was useful to decrease harmful emissions. Sounds strange to mount a similar trigger without essentially cut out some advantages but also this choice is made in anticipation of using the RC standard if ignition resists Dakar means that will fit into any other conditions.
We replaced by half-way onwards once reliability data. Electrical problems have come from an incorrect choice of batteries and an electrical system that during the tests was perfect, While in Africa it was not such a. This particular unit determines the ignition timing according to the speed and diversity of pressure within intake pipes. downstream vacuum carburetor throttle. — Where you changed the bike than the previous Dakar? Last year's race had given us important information: We were in place as engine and chassis, While the handling had to be improved. Since we were unsure in terms of engine reliability, We went to increase performance. We resumed the changes introduced on the RC series propeller 91.
New camshafts more motivated, revised piston design, oversized valves and larger diameter Carburetors (30 mm). We work a lot on intake and exhaust systems rato to extract from the engine to its full potential. Despite the compression ratio was lowered to use low-octane gasoline, We found seven horses more than the previous motion. Now we are about sixty horses to the tree with a consumption that varies greatly according to the conditions of the competition site. They range from a maximum of 6,5 liters on soft sand up to 9 the hard ground. Does not consume little, It's true! A single cylinder must always be squeezed at most to stay close to the performance of two cylinders and then throttle always wide open; extreme conditions also for consumption. In total, the fuel capacity was increased to almost 60 litres, ten less two cylinders.
Not a great advantage. Is a little’ the legend say that mono is easier and lighter of the two cylinders. The weight difference is a maximum of ten pounds in favor of mono and so it's not outstanding. To improve handling and ease of driving we revised weight distribution and placement of fuel tanks. The suspension is new, the Kayaba Japanese, also mounted on the RC-series. The shock is just what standards changed only three internal lamellas to match the increased weight of the bike dakariana, to ease that we used some lightweight material” but nothing special. Kevlar and carbon fabrics for the cowl – rear tank and to the fairing, titanium for engine and rear suspension hardware platforms. For the hubs machined from “full ".
We also broke, and even this drawback we expected, the forward beam where you fix the engine. Between expected and now we solved, because to increase ground clearance we removed the retaining frame which passes under the engine. In this way the engine actually works as element stressed lifting quoting frame. That is why we have strengthened the bolts of the engine by increasing-the diameter up to 10 mm, attack fins simultaneously beefing up on engine. We broke more rods and crankcase, meat instead happened last year; by contrast has almond wafer with a small crack in the frame. This made us realize that the engine can work as an element of stress and probably will use the same solution even in series, Front chassis beam and properly structuring that is another effective information appearing on the series production.
More tears were those of posterior composite tanks. They were all new parts, ended up at practice the day before leaving the tanks have had mechanical problems. The rear suspension dabbed a little’ Too much, so as to touch the disc brake caliper with the inside of the tanks. In the design phase we predicted a game 20 mm between the clamp and tank at full travel of the rear wheel. In bolder touched caliper infill; with inevitable breakups. This means that both the swingarm is the retaining frame that sustains them yielded, sagged slightly. Modified suspension settings, the problem is gone. Conversely decreased comfort of riders and motorbikes squirted a little’ too much on holes.
You are marked for small cracks on the front aluminum tanks because of the numerous welds, the bodywork is broken is broken only for falls, While we can't explain the reason of the break up tree M., why this particular had been thoroughly analyse it. It was also changed the engine in Sotelo, because he was burned out the clutch lever play for lack of. All material of friction discs has spread in the engine and a piece went to lock the pressure relief valve of the oil system. Result: Cotto bearing on fro di bella. For the rest no other mechanical problem except the cushion Pan hastily fastened on the bike by Medardo. —
Your bike aesthetically was the most reused. among all those who have raced, and maybe even more aerodynamic.
"We treated very aesthetics but also the protectiveness of the pilot. We left date filter box dimensions, and we built around the whole bike. We tried to protect the pilot to give him greater comfort. Less tired, stronger you go and commit fewer mistakes. The bike had to be the smallest possible depending on the size of the pilot. The height of the windshield and the de: plexiglass has had the sole purpose of protecting air pressure the pilot We instead chose the headlights omofocali to lower the whole area of the dashboard and Instrumentation, and ensure greater visibility. Also these headlights made even better brightness and then more security to those who remained at night in the desert. The latter form is due to the tradeoff between greater capacity as possible and require less space for the rider's legs. In codon had set the compass, and a back up battery. The shape of the entire casing is designed without the comfort of a wind tunnel. Now we will try the bike in these conditions; We want to be ready on time.
Can you quantify the cost delta operation Dakar?
Only pure material exceeding one hundred million for motorcycles, but the entire organization has quite different and higher costs. We are considering whether it is possible to build a small number of replicas of the RC Dakar. The figure is expected to be around 60 million and it would still be a political price. The difference in costs will be absorbed by the factory»
You will be also present in the next Dakar? "Definitely Yes. The conditions encountered in the Paris-Dakar is practically unrepeatable, both instrumentally both under normal measurement conditions of motorcycle. With the African race we can verify many parts of production motorcycle» though next Gilera RC doesn't compete more in Silhouette. We will build a prototype with a capacity close to 650 CC though probably the reliability cannot be guaranteed one hundred percent».
Source Motorcycle Racing April 1991