Patents Reveal Yamaha’s New Type of Motorcycle ‘Clutch’

A new system is in development by Yamaha, for use on its upcoming electric motocross bike, intended to mimic the clutch on a combustion bike

2023 Yamaha YZ450F
2023 Yamaha YZ450F

Yamaha is developing a ‘clutch’ system for its upcoming electric motocross bike, as revealed in recent patent filings.

Published by Cycle World, the filings show Yamaha’s alternative ‘clutch’ solution to the flywheel-based one it used on its TY-E electric trials bike, but which it decided was too heavy for the electric ‘crosser.

The trials bike used a clutch in combination with a flywheel to act as a kind of energy store. Releasing the clutch would effectively give a power boost.

In motocross, similarly to as in trials, the clutch is an important aspect of the bike, especially compared to other forms of racing, because the clutch is used in places other than the start and gear shifts. In motocross, for example, the clutch is used to control speed, because moving your fingers in and out is quicker and more accurate than rolling your wrist. Riders who are used to combustion bikes and have ridden bikes like the Stark Varg have noted how they would like it to come with a clutch, and Yamaha has maintained a ‘clutch’ lever on the left handlebar for its electric motocross bike.

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2023 Yamaha YZ450F.

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However, it’s not the main lever, as that is reserved for the rear brake in an attempt to remove foot controls. Instead, the ‘clutch’ lever, which appears quite short, is positioned just above the main lever.
Despite the lever’s appearance being unlike that of a traditional clutch lever, Yamaha’s patent document describes its feedback as similar to that of a traditional clutch, meaning deadzones at either end of the lever’s travel with an increasing progressive load as the lever is pulled in.

As for the mechanism itself, as aforementioned, the flywheel system is gone and replaced by a new system. It uses the same basic philosophy of the flywheel system on the TY-E, with energy stored in springs which sit between two discs when the ‘clutch’ lever is pulled in and the throttle is open.

Additionally, the system allows for control of regenerative braking, which would act as engine braking on a combustion bike. By pulling in or letting out the lever, the rider can control how much ‘engine braking’ effect they can feel, just like on a combustion bike.

Yamaha TY-E 2.0.
Yamaha TY-E 2.0.

Yamaha TY-E 2.0 electric trials bike.

The bike’s powertrain is also based on that used by the TY-E electric trials bike that Yamaha has developed in the past few years and which competed at World Championship level. 

Additionally, Cycle World reports that new patents have been filed that relate to the bike’s waterproofing of its powertrain and the addition of breather hoses to manage pressure changes in the motor or battery case, for example. 

Furthermore, Yamaha has implemented a system whereby the rider can input into the bike’s ECU the length of the race they are about to start, and the bike will calculate how much of the powertrain’s total performance can be used to make it to the end of the race with the charge remaining in the battery. It’s an interesting addition, because of the amount of variables between riders, tracks, and even the same track lap-to-lap.

These latest patents show a level of finishing detail that indicates Yamaha’s electric motocross bike could soon be ready for production.

Yamaha would be the second major manufacturer which has a current internally combusting motocross programme to launch an electric model, although the Honda CR Electric Proto is, as its name suggests, a prototype.

Trey Canard, 2023 All-Japan Motocross. - Honda Racing Corporation
Trey Canard, 2023 All-Japan Motocross. - Honda Racing Corporation

Trey Canard on Honda CR Electric Proto in 2023 All-Japan Motocross Championship.

Honda has raced its electric motocross bike in the All-Japan Motocross Championship and in the FIM E-Xplorer World Cup, the latter an enduro-style series strictly for electric bikes.

Recently, Infront Moto Racing announced its new electric-only motocross series, MXEP, which will run as a support class to the MXGP World Championship. The announcement of the series received opposition from Stark Future - the leading electric manufacturer in motocross with its Varg model that won the UK Arencacross series this year - but could be an option for both Yamaha and Honda when it launches in 2026.

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