Mugen E.Rex concept

Famed Honda tuner Mugen has used the Tokyo Motorcycle Show to reveal its concept of an electric motocross bike – the E.Rex.

The bike is based on Honda’s CRF250R crosser. That’s no surprise, as Mugen is closely tied to Honda, having been founded by Soichiro Honda’s son and building its business tuning Honda’s cars and bikes. But the 250cc single-cylinder engine is replaced with an electric motor and battery pack.

Most electric bikes, like Mugen’s own Shinden, which have their entire chassis built around the requirements of batteries and an electric motor. The E.Rex is different. It features a purpose-made motor-and-battery unit that’s intentionally designed to ape the shape of a conventional petrol engine and its airbox. That means it can be slotted straight into an otherwise-stock bike.

The motor itself is near the bottom of the package, with a distinctive turbine that helps air flow through it and keep it cool. It drives through what appears to be a single-speed reduction transmission to a conventionally-placed front sprocket. With no need for a clutch, the rear brake is relocated to the bars, leaving the bike with no foot controls at all.

There’s also a water-cooling system that uses the stock radiators from the donor CRF250R. As well as helping keep the motor cool, it presumably keeps the battery temperature down. Anyone with a smart phone will know that when under heavy use, lithium battery packs can get pretty warm. The water cooling on the Mugen will help remedy that.

The firm hasn’t revealed details of the bike’s performance or range. As a competition-style motocrosser, long range isn’t likely to be a priority, but keeping the performance high and the weight low will be.

Mugen also hasn’t revealed whether there are any intentions to put the bike into production. If it does, or if Honda does, it’s likely that the weird skeleton-style bodywork that backs up its dinosaur-derived name would be swapped for something more conventional. Which would be good…