Digital speed limiter with Magnet double-check and auto-reactivate for digital control of speed and revs. Function: at its heart, the speed limiter has a powerful microprocessor which constantly calculates and evaluates the speed and revs. Speed is picked up via a wheel sensor and magnet fitted to the wheel. The RPM is calculated directly from the pick-up cable on the CDI unit at each rotation of the crank. The limiter can be used in KMH, RPM or combined mode. KMH mode: in MKH mode you can pre-program a top speed and when this speed is achieved, the scooter is restricted by a drop in the RPM. The limiter incrementally restricts the RPM as the scooter moves towards the upper limits of the pre-set rev range. Under this max speed limit the scooter is completely unhindered. Unlike other units, this has the benefit that acceleration and hill riding are not negatively affected. In order to use KMH mode the wheel sensors (included) and the wheel magnet (also included) must be installed on either the front or the rear wheel. RPM mode: here the wheel magnet is not required as the scooter is simply restricted by a pre-determined RPM limit. When the maximum RPM is reached, the scooter is restricted accordingly. This also means that the scooter is not restricted in the lower rev range or anywhere below the pre-set limit. In order to reduce the effect of a sudden restriction in power, pre-set stages can be programmed in which the limiter restricts every third cylinder impulse. Combined mode: This is particularly useful for restricting a high-revving engine to a low top speed. To ensure the engine doesn`t simply rev freely, you can reduce the max RPM shortly before hitting the top speed. Programming and control: Programming the top speed / maximum RPM limit is, thankfully, very simple. A simple touch of the Program button is enough to save the current speed or RPM limit. To deactivate the limiter, simply apply the brake and press the button at the same time. To re-activate, you simply have to turn the ignition off and back on again. Dimensions: the housing is a tiny 45x45x18mm + fixing mount. The length of the connection cable is 45-50cm and the button cable is about 1m in length. The wheel sensor is a mere 28x19mm with a cable length of 50cm. Note: the original cable length of the wheel sensor is way too short at 50cm, especially if mounting to the front wheel or hub. You receive an additional 4 quick connector cables that make short work of installation! No need to cut or solder the loom. Installation: all 4 cables from the limiter need to be connected. The unit requires a 12v supply (activated via the ignition barrel), a brake signal, pick-up signal and an earth. For the KMH mode you need to additionally install the wheel sensor and the wheel magnet on the front or rear wheel. The sensor picks up the wheel revolutions just like a bicycle speedo. The camp between sensor and magnet should be 5-15mm. The wheel sensor is best fitted between the wheel and the variator cover, frame or fork. The magnet is fitted with a 3M adhesive layer and can easily be fitted to the wheel rim or the inside of the brake disc. Although the magnet is self-adhesive, we recommend permanently securing the sensor in position with a 2k glue once you have found the optimal position. Inside the limiter there are two control LEDs to check for correct installation and functioning. Digital vs analogue: why this item over a standard analogue limiter? Analogue limiters are generally fitted with 4 condensers that need to combine with an RPM cor or DIP switch in order to ascertain the RPM limit. 4 condensers means only 15 stages at which an analogue limiter can be set. Controlling the limits is therefore vague and can mean that you are unable to program your desired RPM limit at all. This could mean that stage 12 is too restricted, where stage 11 is not restricted enough. None of this is an issue with this digital limiter, which can be seamlessly adjusted for the desired RPM range. The digital limiter only alters the spark once the upper limit has been reached meaning no loss of power or acceleration in the lower rev range. Benefits:Digital control of speed and RPMSpeed / RPM or combined mode seamlessly adjustable for different stages of restrictionNo restriction of power or acceleration under the pre-set speed limit set in KMH modeIdeal for acceleration and hill ridingNo loss of performance in the lower rev rangeAutomatic restrictor activationDouble check: simultaneously pulling brake lever is required. Very safe!Quick connector cables - no need to cut or solder.Top quality: all components are carefully secured to the housing (increases longevity of product)Delivery includes: KMH-RPM restrictor, 4 quick connector cables, wheels sensor and self-adhesive wheel magnet, step-by-step installation instructions with wiring diagram. Compatibility: The restrictor works with almost all 2-stroke carbureted machines (such as the common Minarelli-style scooters [1E40QMB] such as CPI and Keeway. Not compatible with 4-stroke machines with direct injection, Morini engines with double pick-ups (e.g. Aprilia SR50 with brown and white CDI cables).