The clutch – a key component in a scooter transmission

Function of a scooter clutch

As on a motorcycle with a manual transmission, the clutch’s job is to disconnect or connect the engine and the drivetrain. The difference: on a scooter, it is a centrifugal clutch. It engages automatically as soon as a certain engine speed is reached.

Several components work together: the crankshaft drives the variator, which moves the V-belt and the torque driver on which the clutch is mounted. The centrifugal clutch has clutch shoes that are held closed by springs. As RPM increases, rotational speed and centrifugal force increase - the shoes open and engage the clutch bell. This drives the transmission and the wheel. Direct operation of the clutch is therefore not required.

Scooter clutch and engine setup

Here too, as with a motorcycle: if performance increases, the clutch must be adapted accordingly. On a scooter, this is not only about reliability and preventing slip, but also about the engagement point. A centrifugal clutch can be adjusted very precisely.
The stiffness of the clutch springs directly impacts the clutch engagement point. Replacing or re-tuning them is therefore especially useful after upgrading to an engine setup designed for high RPM.

Recommendations:

Depending on the tuning level (setup), it is not necessarily required to replace the complete clutch. However, readjusting it is usually essential.

• Switching from a stock exhaust to a performance exhaust? Then stiffer springs are required.
• Upgrading your scooter with a more powerful cylinder? Then a reinforced clutch should be considered. It is more durable and less prone to slipping.
  → Example: Stage Sport Pro
• Building a true racing engine with a very peaky powerband (lots of power, but only within a relatively narrow RPM range)? Then we recommend a clutch that is both reinforced and offers many adjustment options (spring preload, weights, etc.).
  → Example: Stage Racing Torque Control

In addition, another clutch component can be crucial: the bell. The more powerful the engine, the more likely the clutch is to heat up significantly. That is why the bell should also be chosen appropriately - ideally a ventilated model that matches the clutch.

Identifying defects and incorrect settings

A worn clutch or incorrect setting can often be identified without even having to open the clutch.

Typical wear symptoms include: the clutch slips, there is a strong smell of overheating (visible heat marks on the bell and damaged friction material on the shoes), engagement is difficult or no longer happens at the correct point (springs are fatigued and stretched).

Typical signs of incorrect adjustment are:

• The engine revs very high before the clutch engages, and off-the line acceleration is jerky: springs too stiff or too much preloaded.
• The clutch engages at too low an RPM, take-off is sluggish, and the scooter takes several seconds to build speed: springs too soft or not enough preloaded.

To make installation easier, there is a video tutorial on our channel.

Scooter clutches in our shop:

In our online shop you will find everything needed for maintenance, tuning, and optimization of the scooter clutch. We offer complete clutch kits in both OEM and reinforced versions, as well as all clutch components individually: springs, bell, accessories, etc. We carry parts from renowned manufacturers such as Malossi, Polini, Stage6, Motoforce as well as matching components for popular models such as MBK Booster and Nitro, Piaggio Zip and Typhoon, Peugeot Speedfight and Kisbee, and more.