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- Vespa Modern
- KÜBLER Rear ABS Sensor Wheel, Z=44, Silver, for Vespa GTS 125-310, GTV 300-310
Up to 10 km/h more top speed without modifying the engine? This is exactly where the KÜBLER Racing Z=44 tone wheel comes into play. Developed specifically for 12-inch wheels, the ABS sensor ring changes the way the rear wheel speed is detected, allowing the available performance potential of the Vespa to be used more effectively. A technically clever, virtually invisible and fully reversible solution for ambitious Vespa GTS and GTV setups.
The principle behind it is as simple as it is effective: the tone wheel is a slotted steel disc mounted on the rear wheel. Its windows pass the ABS sensor while riding and generate the pulses used to determine wheel speed for the ABS and ASR control systems. The Z=44 version features 44 precisely arranged sensor windows and is designed for use with 12-inch wheels.
The Vespa GTS HPE delivers more power at the rear wheel than its predecessors. However, this additional potential cannot be fully exploited in terms of top speed in standard configuration. One reason is the noticeably optimistic speedometer reading. At an actual 120 km/h, the speedometer may already indicate approximately 130 km/h. At an indicated speed of around 130 km/h, the vehicle electronics intervene and limit further acceleration.
As a result, the engine's potentially achievable top speed is not necessarily reached. The electronic limitation can already intervene even though, depending on the vehicle setup, sufficient engine power may still be available for a higher actual speed.
This is exactly where the KÜBLER Racing tone wheel makes the difference. Its modified geometry with 44 sensor windows changes the way wheel speed is detected. As a result, the speed signal transmitted to the vehicle electronics corresponds much more closely to the actual road speed.
What may initially sound like electronic tuning is based on a simple mechanical principle: the speed limiter can intervene approximately 10 km/h later. Where the Vespa may reach only around 120 km/h actual speed while displaying 130 km/h in standard configuration, after the conversion it can achieve around 130 km/h actual speed at the same indicated 130 km/h.
The actual achievable top speed still depends on the available engine power, vehicle setup, rider weight and the respective riding and environmental conditions.
The particular appeal of this solution is that no engine modifications are required. The engine, fuel injection system and internal engine components remain untouched. The tone wheel only changes the detection of the wheel speed.
The conversion can easily be returned to standard specification and is virtually invisible from the outside once installed. As the tone wheel itself neither increases engine power nor modifies the engine mechanics, the component does not cause additional mechanical engine wear.
This Z=44 version is designed for Vespa GTS and GTV models with 12-inch wheels. Its 44 rectangular windows are evenly distributed around the circumference and form the geometry that is crucial for speed detection. This distinguishes this version from tone wheels with a different number of windows, which may be intended, for example, for conversions to a different wheel diameter.
Visually, the KÜBLER Racing tone wheel is also uncompromisingly functional. The flat silver steel disc features five mounting holes, a generously cut-out inner contour and evenly spaced rectangular sensor windows. The surface also carries the marking “only for race”.
On vehicles from Euro 5+ onwards, a tone wheel with the same number of windows must also be installed on the front wheel. If the KÜBLER Racing Z=44 tone wheel with 44 windows is installed at the rear, the front tone wheel must therefore also have 44 windows. On these vehicles, the front and rear wheels must be equipped with the corresponding identical number of sensor windows.
The tone wheel is installed on the rear wheel. To gain access, components including the exhaust and swingarm on the right-hand side of the vehicle must be removed. After replacing the tone wheel or tone wheels, the ASR system must be recalibrated on vehicles equipped accordingly. Correct calibration is an essential part of the conversion and must not be omitted.
The effect of the conversion can be demonstrated particularly well with a GPS speed measurement. The actual top speed can be measured before the conversion, for example using a suitable smartphone app, and then measured again under conditions that are as comparable as possible. This makes it possible to see at which actual road speed the limiter intervenes before and after the conversion.
The KÜBLER Racing Z=44 represents a particularly clever approach to Vespa tuning. Instead of generating additional engine power, it allows the performance already available to be used more effectively. No opening of the engine, no conspicuous add-on components and fully reversible – just a precisely designed steel disc with 44 windows that makes the crucial difference in exactly the right place.
Note: The tone wheel is marked “only for race” and is intended for racing use. No ABE/TÜV approval; use on public roads is only possible following individual approval where legally permitted.
