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CASE STUDY: PROJECT DRAGSTER
The Dragster looks like no other scooter in the world. The Dragster is engineered around an open trellis frame similar to its Italian big brother, Ducati. Italjet's patented Independent Steering System (SIS), with a horizontal hydro-pneumatic shock that rides between your legs is truly a work of art. The front swing arm rotates through a very small arc, thus allowing the wheelbase to remain almost constant when cornering. Because of the (SIS) system, mounting points for the front and rear swing arms is very short which allowed Italjet to make a chassis that is very rigid. Steering forces from the handlebars are transferred to the front wheel through lightweight articulated rods that pivot on the front swing arm. The advantage of the (SIS) systems vs. classic scooter type trailing link or motorcycle telescopic forks is obvious from the second you ride it; there is virtually no front end dive when you're hard on the brakes. This makes it possible to trailbrake the Dragster mid-corner without upsetting the scooter or affecting your desired line. The Dragster's rear suspension consists of a three piece alloy swing arm and transmission case that pivots on a centrally mounted hydraulic monoshock. Very cool!! This state of the art suspension and very low center of gravity, along with fat Michelin tires and lightweight five spoke alloy wheels, allows the Dragster to handle like no other scooter. Italjet also dropped the handlebars in order to shift the riders position and weight over the front wheel for increased traction in the twisties. The Dragster's brakes consist of a 175mm hydraulic front vented disk and a 190mm hydraulic rear vented disk coupled with steel braided brake lines and a weight of only 85kg. This combines to make stopping the Dragster an eye popping experience! Other cool items on the Dragster are: electric and kick starters, automatic choke, CDI electronic ignition, under the seat storage, race-style gas filler, chromed dash with white faced speedo and a vast array of warning lights. One even gets a lockable storage compartment for a cell phone! You would assume by the name and looks of this scooter that it was a 150cc to 200cc scooter. Some are amazed (and some even disappointed) when they find out that it is only 50cc! In Europe, there are bigger versions available, but there is rumour that we may see a 180cc four stroke version here next year. Nevertheless we still prefer the two stroke, even if it is smaller. When these scooters come into the U.S. their motors are very restricted. Fortunately, without spending a dime you can almost double the speed of a stock Dragster by removing these restrictors (there are two restrictors located in the exhaust system and one in the variator assembly). With the restrictors removed, top speed is 40-50 mph, so don't be fooled by the little 50cc liquid cooled Minarelli engine. This is the same Minarelli motor used in other high performance scooters in Europe, including the new Aprilia 'Area 51' & SR Replica scooters. While these speeds might be fine for most, NOT FOR US! Our project started by replacing the stock 50cc cylinder with a 70cc Malossi M.H.R. (Malossi Hyper Racing) aluminium racing cylinder. The cylinders were originally designed specially for the 1995 International Scooter Trophy Cup Race in Europe. The cylinders are engineered for maximum performance. While, at the same time, assuring extremely long life. The compression ratio is 13.8:1 with a torque value of 7.35 N.m (.75Kgm). The stock metal reeds were replaced with Malossi carbon fibre reeds for faster throttle response. A Malossi kevlar reinforced drive belt was then installed for strength and smoother acceleration. The stock 12mm Dellorto carburettor was replaced with a 22mm hi-performance version, while retaining the stock automatic choke and throttle assembly. Because of the increase in power and torque, the stock variator cannot allow the Dragster's transmission to engage within the peak powerband. So, we installed a Malossi multivar adjustable variator and played with the different weights until the desired powerband was achieved. Getting the correct weight combination, however, depends on the modifications being done, powerband desired, and riding style. We also found that the use of the Malossi torque driver greatly improved the scooters powerband. Its function is to determine the precise moment when to engage. It has been designed to give the Dragster maximum possible acceleration according to the specific size of each motor. The special shape of the Malossi torque driver was designed to keep the RPMs fixed at the point of maximum power. The use of the torque driver allowed us to fully exploit the modifications we made to our Dragster while still maintaining very gradual and fluid delivery of torque to the rear wheel. With our intake and transmission modifications complete, we turned to the exhaust system. While the stock exhaust may look cool, it's very heavy and does not take advantage of the engine modifications. As the importer for Arrow exhaust systems, it was my obvious choice for our project. The Arrow 'Limited Series' chamber is hand made just for this Minarelli engine with 70cc cylinders installed. This pipe is a work-of-art in itself, from its hand braised welds to its carbon fibre/kevlar silencers, to complete protection with a special glossy clear coat. Arrow also make the 'Kompress Series' for stock Dragsters. We picked up over 14 mph with the exhaust chamber. Is it noisy? YOU BET, but it sounds great!!! Power is very smooth and linear. Our motor setup pulls hard up to about 35 mph, then tapers off until it hits 50 mph, then pulls hard again to 65 mph. Our Dragster cruises great at 65 mph, with a top speed of about 80 mph. While our total investment is around $1000 (parts only, labour not included), it does not have to stop there. There are still several performance upgrades that can still be added, such as: racing drive shafts, driving gears, secondary gears, gas charged shocks, electronic power units, and adjustable clutches. Malossi has recalculated the transmission ratio gears in super strong hardened, tempered, molybdenum chrome steel. These straight cut gears are interchangeable with the originals. The shaved straight cut tooth gives maximum power transmission, it also reduces vibration and saves a significant amount of energy. We estimate top speed somewhere around 90 mph with all modifications installed. Stay tuned... For the most part we found these kits to be 'bolt-on', although we did have to swap some parts, adapt others, tweak some and even grind another. With the right tools and good mechanical skills, the kits take about 5-7 hours to install. Our project Dragster now shows 965 miles and has had no problems; it averages 80 mpg, costs about $8 a month to insure, and looks 'out of this world'. Wanna Drag?
Words & Pictures: Kregg Williams.
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