What is an automatic motorscooter?
Automatic motorscooters, a.k.a. "twist-n-goes", a.k.a. "plastic scooters", are confusing at first. They're motorscooters because they have (generally) small wheels, a step-through body, and the engine/transmission swings with the rear tire. By definition, they have automatic transmissions.
Instead of manually disengaging a clutch and shifting between three or four gears, automatic scooters employ a centrifugal clutch and pulleys to transmit power from the engine to the drive wheel. This makes them easier to drive, and thus popular amongst those who just want to ride the darn thing to work and back.
Automatic scooters were invented in America, and the first example of a functioning automatic scooter was the Salsbury Motorglide of the 1930s, followed by the Salsbury Model 85 of the 1940s. These were steel, of course, as as the currently produced Vespa ET series, Italjet Velocifero, LML, Piaggio, and Bajaj classic-style scooters. All other automatic scooters are steel frame covered with a plastic body.
Automatic scooters are easier to ride, because they shift themselves, but that may or may not be an advantage when racing. Different techniques are used when racing automatics. See below.
return to top of page
Who makes automatic scooters?
Today nearly all motorscooters produced are automatic, whether they be steel- or plastic-bodied, two- or four-stroke. To my knowledge, the only manually-operated transmission motorscooters produced today are the Piaggio, LML, and Bajaj.
There are a variety of manufacturers of automatic scooters. Here's a partial list, along with the country of origin.
return to top of page
| Maker |
Origin |
US Sales |
|
Maker |
Origin |
US Sales |
| Adly |
Taiwan |
|
|
Aprilia |
Italy |
Aprilia USA |
| Bajaj |
India |
Bajaj USA |
|
Benelli |
Italy |
|
| Beta |
Italy |
|
|
BMW |
Germany |
|
| Daelim |
Korea |
|
|
Derbi |
Spain |
|
| EVT |
Taiwan |
|
|
Fosti |
China |
|
| Gilera(Piaggio) |
Italy |
|
|
Honda |
Japan |
|
| Hyosung |
Korea |
|
|
Italjet |
Italy |
|
| Kangda |
China |
|
|
KYMCO |
Taiwan |
|
| LML |
India |
|
|
Malaguti |
Italy |
Malaguti USA |
| MBK |
France |
|
|
Motorama |
Taiwan |
|
| Peugeot |
France |
Peugeot USA |
|
PGO |
Taiwan |
|
| Piaggio |
Italy |
|
|
Rovigo |
Taiwan |
|
| Siamoto |
Italy |
|
|
Suzuki |
Japan |
|
| SYM |
Taiwan |
|
|
Taishan |
China |
|
| TGB |
Taiwan |
|
|
Vespa(Piaggio) |
Italy |
|
| Yamaha |
Japan |
|
|
Zhongyu |
China |
|
return to top of page
How does an automatic work?
Automatic transmissions in scooters do not function the same as automatics in cars or trucks. Automatic scooters have a continuously-variable transmission (CVT). When the engine rpm increases to a set point, the centrifugal clutch begins to engage. The rpm at which this happens is controlled by springs and weights. Instead of shifting between 3 or 4 gears, the automatic scooter transmits power from the engine to the rear wheel by pulleys, a belt, and a secondary gearset. As the engine and rear wheel speed increase, a device called a variator adjusts the size of one of the pulleys, thus altering the drive ratio.
At start, drive pulley "b" (the one on the engine) is smaller than driven pulley "a" (attached to the rear wheel). This gives the engine more leverage to get the scooter rolling. As vehicle speed increases, the variator continuously varies the diameter of the drive pulley, making it relatively larger than the driven pulley. This makes the driven pulley spin faster while the drive pulley still turns at nearly the same speed. Think of how changing gears on a ten-speed bike affects your speed: when you switch from the small front sprocket to the larger one, the bike goes the same speed, even though you're pedalling at a slower rate. To complete this analogy, imagine increasing your pedalling rate until you're pumping just as fast as before you shifted, but now the bike is going faster. But remember, the CVT doesn't instantly jump from one size sprocket to another, it gradually increases the size of the pulley.
At start |
At speed |
Unlike manual transmissions and automatic transmissions found in cars and trucks, the engine does not increase speed during acceleration, then slow down again when a higher gear is selected. Instead, the engine maintains a relatively constant rpm while the variator continuously varies the relative size of the two pulleys. Car makers have attempted to build vehicles with CVTs, but none have withstood the stresses involved in automobiles. CVTs are well-suited for light vehicles such as scooters, but can't handle the weight and power of cars and trucks. Even in scooters, the drive belts usually must be replaced every few thousand miles. This is a nuisance in scooters, but would be a major drawback in passenger cars.
return to top of page
Can I race an automatic scooter?
Hey, you can race your riding mower. You can race a bed. You can race a school bus. Why not race your motorscooter? Of course you can race it, you just have to find a place and someone willing to go up against your 50cc fire-breathing monster.
That latter part might not be as easy as it sounds. A lot of people who ride scooters, both automatic and classic, are wussies. Now don't get me wrong, I've got nothing against wussies. In fact, I used to be one myself. But, I grew out of it in time.
There's a good chance that your wussy friends will grow out of it, too. Don't try to force them, or they will probably withdraw from you, spouting verbage about "safety" and "sanity", whatever that is. You can just set a good example for them, and hope they develop hormone-producing organs. Some of them never will, sadly, but that's life, right? Screw them, and find some new friends.
Or better yet, turn them into your pit crew, or groupies, or something useful. Hey, we need corner workers and fans in the stands, too. A wuss with a good tool kit and a pickup may be worth the effort, after all. Yeah, alright, that settles it, the wussies can stay, but only if they help out somehow.
Glad that's settled.
return to top of page
What's it like to race an automatic scooter?
Autos have some advantages and disadvantages over manuals. On the one hand, automatic scooters are handicapped because they're just that . . . automatic. The "shifting" and engine speed control are set and can't be changed without adjusting or replacing internal parts. Manual scooters are more easily controlled by the operator. The rider of a manually-shifted scooter can choose when to shift, what rpm to shift at, or not to shift at all. Not as simple with an automatic. As far as I know, there is no scooter yet available which can switch modes at the whim of the rider, the way a manual can.
The actions of the variator and the clutch, as well as the ratios of the secondary drive gears, are all set at the factory to meet the needs of the "typical" user. Most buyers will want the scooter to last a long time, get good fuel economy, and provide reasonable performance. The factory specs try to balance these conflicting needs, and most folks will be moderately happy with the results.
The difficulty lies with taking a stock street automatic scooter onto the track. With a manual scooter, the rider decides when to shift, how high to rev the engine, when to use the engine as a brake, etc. With an automatic scooter, the rider has little control over this, short of adjusting or replacing internal parts. Then, he's stuck with whatever he set up until he changes it back. On a manual scooter, a person can putt-putt up to the track shifting at low rpms to conserve fuel, then adopt a radically different style of riding once on the track. The automatic rider can't as easily change between modes.
In manuals and automatics, gears can often be changed to accomodate needs for different tracks, to match the powerband of the engine with the speeds at which the scooter will be expected to attain. That's similar in both types of scooter, in that it's not something you can do while riding. You could, however, swap gears for the race and then swap them back again for the ride home. In theory, anyway.
Another difference in racing automatics is the inability to use the engine as a brake when coming into a corner, then having it in the perfect gear and instantly applying power out of that corner. Manuals can do this, automatics can't. When power is removed on an auto, as by releasing the throttle, the engine rpm drops and the centrifugal clutch disengages. No engine braking there. Then when power is re-applied there's a brief lag whilst the clutch re-engages and the variator re-adjusts to the new circumstances.
To compensate for this, automatic racers may maintain a high power setting while decellerating into corners, in order to maintain clutch engagement and keep the engine and variator turning at the correct speed. This reduces the lag problem, but introduces a new potential problem of brake fade.
An advantage to racing an automatic is that you hardly ever miss a shift. Oh, you can burn out clutches (just ask Tim Youngblood about that) and you can break drive belts, and other mishaps can befall an auto, so they're not the answer to all your problems.
return to top of page
Additional resources about automatic scooters
TWIST & GO Scooter Magazine® is the most complete print resource I'm aware of. Published monthly in the UK by Scootering Magazine®, and available at many scooter shops as well as by subscription. Three websites: www.scootering.com , www.scootertrader.com , and www.twistngo.com .
return to top of page
