A minibike, also recently known as a mini moto or pocketbike, is a miniature motorcycle. Most traditional minibikes use four stroke engine to turn the rear wheel via a chain. Small cheap gasoline engines like ones produced for yard equipment are most often used, though most designs require a horizontal crankshaft engine. This means that typical walk behind mowers, which use vertical crank engines, cannot be used. Some models use a two stroke engine, and electric-powered models are also available. A 2-stroke engine usually creates a louder, higher frequency noise then a typical four-stroke engine, this is because a two-stroke engine has a power stroke, and subsequent exhaust pulse every rotation of the crankshaft, while a four-stroke has a power stroke, and an exhaust pulse every other rotation of the crankshaft. In effect, two-strokes sound as if they are operating at double the speed of a four-stroke engine. Also, an improperly tuned two-stroke often releases unburnt fuel, and thick blue smoke out exhaust during normal operation, these features, along with a minibike's small size, mean that minibikes are rarely street-legal.
The concept of pocketbikes comes from Japan . The first pocketbikes appeared on the market, a super-fast 2 ft. high, 3 ft. long motorcycle that is "supercool". in the 1970s and '80s , originally costing up to $4,000 .
Like go-carts, the first minibikes were made by enthusiasts from spare parts found in their garages. They were first popularly used as "pit bikes", for drag racers to travel around in the pits during races in the late 1950s. They were very useful for this purpose, as they could maneuver very well in the tight pit roads, fit in about the same space as a small bicycle in a trailer or pickup, and they were faster than most previous forms of transportation. As racers brought them home and used them around their neighborhoods, many children liked the idea of having a "mini motorcycle" and started building their own. A market for minibikes developed and many cottage and major industries developed to meet the demand. Famous minibike companies include Arctic-Cat, Rupp, Taco, Heath, Gilson, and Fox, many of which also made other power toys such as go-carts, trikes and choppers. The height of the minibike/go-cart era was from the late 1960s to the early 1970s in America. Many of the famous brands, foremost Rupp, have gained a cult-following of enthusiasts and owners.Early Minibike Powertrain These early minibikes usually consisted of a powertrain containing a small fourstroke, horizontal shaft, flathead engine. The power tansmission usually consisted of a crank-mounted centrifugal clutch and chain drive to a rear sprocket. As the minibike and the mini-powersports field grew and expanded, Comet intriduced a small variable-ratio belt system (much like a snowmobile's) called the Tourque-a-Verter, which allowed for the better tansfer of power from the engine to the rear wheel, reulting in better top speed and acceleration.
These tickets could all up to over $2200, so a joyride can get pricey fast. Now that's a worst-case scenario, but pocket bikes are illegal for public roadway usage and are intended only for private property or off-road use.
Some of the larger "super" pocket bikes, most commonly the X18, X19, and X22 meet all the requirements and can be registered for legal street use in most states. These bikes have headlights, turn signals, tail/brake lights, a horn, and speedometer, and can also do the speed limit in most scenarios(typically 4 stroke bikes can reach speeds of 55mph). In many states all you need to do is add a rearview mirror and a license plate bracket, but check with local DMV authorities for exact requirements. In some cases if the bike requires minor modification to meet requirements, you may be able to register it as a "unique/homebuilt" vehicle afterward.
Like a full-size motorcycle, the rider must carry insurance, have a current inspection, and wear a helmet if local laws require it. Depending on if your state classes a pocketbike as a "moped" or full "motorcycle", you may or may not need a special motorcycle license and a regular driver's license may suffice.
In general no bike is ready to go on the street out of the box. Riding on public roads without registration is illegal anywhere and at your own risk. The "super" pocket bikes typically are FMVSS certified, check the retailer's site or call them for information. Most times a Manufacturer's Statement of Origin is required to register, if you plan on putting your bike on the street you should ensure that this is included.
Minibikes are not manufactured to meet these requirements, and would need to be modified significantly to do so. Reported instances of this occurring are incredibly rare, meaning that it is very unlikely that minibikes can actually be registered for road use. However, where a minibike or other vehicle does not have ECWVTA, it might conceivably pass a Motorcycle Single Vehicle Approval (MSVA) inspection which would result in a Ministerial Certificate of Approval, permitting it to be road-registered.
In addition to the Vehicle Type Approval, to be ridden on the road the minibike must be registered with the Driver and Vehicle Licensing Agency, display a valid road tax disc (vehicle excise duty), and the driver or rider must be aged 17 or over (or 16 if the vehicle meets the definition of a moped), have an appropriate driving license, have vehicle insurance covering the vehicle's use and wear a suitable motorcycle helmet. The only exceptions relate to electrically-assisted pedal cycles and mobility aids for disabled people.
In the UK in 2005 and 2006, minibikes became the focus of concern about road traffic safety and anti-social behaviour, when seven deaths – five young people and two adults – were attributed to them by the Royal Society for the Prevention of Accidents.
During August 2006, the UK Government ran a campaign to highlight the dangers of minibike misuse on roads and their anti-social use. A guidance document was produced to provide police and other agencies with practical information to deal with the issues and prevent misuse. The guidance outlined the legal status of minibikes and included information on enforcement measures and the provision of legal sites.
More recently the tragic death of Abbi Perrin from Louth has brought the dangers back into public view. BBC News "Man jailed over mini-moto death"
Police will seize, destroy and often prosecute the riders when caught riding in public .
As with a full size bike, the rider should wear a helmet and protective clothing, even for off-road use. You don't have to be going highway speeds to get painful road rash, it can happen at 10mph. Professional mini-moto racers wear full leather suits like GP racers. While a leather racing suit is beyond most people's enthusiam, a good helmet and some knee/shin pads should be minimum.
A good rule is to treat your mini/pocket bike as you would a full size motorcycle.