Lambda Sensors - at SIP Scootershop
In recent years, Vespa riders and dyno operators alike have recognised the value of Lambda Sensors. This simple Replacement Parts eliminates the guesswork by clearly indicating whether the Engine is set too rich or too lean. It eliminates the need to develop an "ear" for the correct Carburettor setting. It also gives a safe feeling on the motorway, as you can see directly on the display that the Engine is running optimally and is not set too lean.
Ideal combustion with the Lambda Sensor
Lambda Sensors are designed for the electronic control of modern combustion engines and play a central role in monitoring fuel injection. They measure the residual oxygen content in the exhaust gases to determine whether the correct amount of fuel has been supplied and whether the Engine is running with too high or too low a fuel content. A lambda value of 1.0 signals ideal combustion, where 14.7 parts air are burnt with exactly one part premium petrol. If the Engine is running too lean, the air values are above 14.7 or above 1.0; if it is running too rich, these values are correspondingly lower.
Lambda Sensors for (almost) every Exhaust
The Lambda Sensor, which is screwed into the Exhaust, now makes it possible to recognise directly whether the Engine is running too rich or too lean. In the past, it was necessary to install an external additional instrument on the scooter, but this is no longer necessary. Thanks to the new adapter kits on offer, the Lambda Sensor can be connected directly to SIP Speedometers. The measured lambda value is displayed on the Temperature Gauge of the speedometer. The range includes various exhaust systems that offer connections for both Exhaust Gas Temperature Sensors and Lambda Sensors. This allows precise monitoring of the engine condition in different driving situations, such as in the partial load range, at full throttle or on the motorway, in order to always know whether everything is in the green zone.
The SIP-Road 3.1 has also been added to the range, a standard racing exhaust that fits almost all cylinders and has welded-in nuts. For owners of exotic or older exhaust models, a kit is available that includes the Lambda Sensor and weld-in nuts to modernise existing exhaust systems. The Lambda Sensor in the kit is heated and requires a power supply, which is provided via a black box. The sensor connection is connected to the measuring input of the speedometer to ensure efficient data transmission.
The Lambda Sensor and the A/F Converter
The SIP A/F Converter enables a Lambda Sensor to be connected to the SIP Speedometer/Rev Counter. This is done via the Connection that is normally used for the temperature sensor. The AFR value (Air Fuel Ratio) is then displayed instead of the temperature such as the Cylinder Head or ambient temperature. A value of 147 on the Display corresponds to an AFR of 14.7, while 160 indicates a mixture that is too lean with an AFR of 16.0 parts air. For a performance-optimised carburettor setting, however, the AFR of 14.7 is not ideal, but a slightly richer mixture with a lambda value of 0.85 or an AFR of 13.5, which also improves the internal cooling of the Engine through the fresh gas mixture.
When connecting the A/F Converter to the SIP Speedometer/Rev Counter, no temperature sensor can be connected at the same time. Detailed Mounting Instructions are included for installation in the vehicle. On the newer types of SIP performance racing exhaust systems, the Lambda Sensor can be screwed directly into the welded-on Lambda Sensor nut provided. For exhaust systems that do not yet have a lambda sensor attachment, a separate weld-in nut is required, which can be ordered in steel or stainless steel as required.
Broadband Lambda Sensors
The type LSU 4.2 broadband Lambda Sensor is heated and requires a robust power supply. The combination of our SIP Performance Ignition with a Battery is recommended for this. Despite widespread opinions that Lambda Sensors are unsuitable for operation in 2-stroke Engines, our experience shows the opposite. If the Lambda Sensor is not used for a longer period of time and the vehicle is running with an extremely rich setting, it is recommended to remove the sensor from the exhaust system for protection.
The Lambda Sensor display is extremely useful for fine-tuning the Carburettor. A lambda value of 1.0 indicates stoichiometric combustion, where the amount of air supplied contains just the right amount of fuel for clean combustion; the ratio is 14.7 parts air to 1 part fuel. Values above 14.7 indicate a lean mixture (e.g. 16.0), while values below 14.7 indicate a rich mixture (e.g. 13.5). Broadband Lambda Sensors have a considerable current requirement of around 1 A and even up to 3 A during the warm-up phase, which is why the use of a Battery in the circuit is recommended.
