olee Posted September 5, 2019 Posted September 5, 2019 Yamaha have revealed their most powerful WR250F enduro to date, complete with a YZ250F motocross-derived engine, new chassis and revised suspension. Now in its twentieth year of production, this latest incarnation promises to be "the most advanced 250cc four-stroke enduro bike ever built by Yamaha," with the closed-competition-only machine also receiving multiple fuel maps, which can be customised using an app on your smartphone. Revised engine Available from October 2019, at the beating heart of the updated machine lies a 250cc reverse-head, single-cylinder four-stroke engine, complete with a new forged aluminium piston for an increased compression ratio. Alongside this come revised exhaust cam timing and intake port valve seats, boosting the bike’s low to mid-range torque. Elsewhere, Yamaha have also done away with the previous bike's 10-hole injector and replaced it with a 12-hole alternative, complete with a 44mm Mikuni throttle body. Just some of the many alterations to the engine, the revisions have resulted in a claimed increase in power throughout the entire rev range, as well as greater performance at higher RPMs. Shaved weight For added poke, Yamaha have also shaved weight, adding a lighter, more compact 390W starter motor, alongside a less-substantial, more durable clutch. Elsewhere, the bike has also gained a new bilateral aluminium beam frame, complete with straight fuel tank rails to help improve feedback on the trails as well as achieve around a 15% improvement in rigidity. Mounted on the new rails is a larger capacity fuel tank, with capacity boosted by 0.5 litres to 7.9 overall. To gain the extra space, Yamaha have extended the tank downwards towards the centre of the bike, helping to improve the overall balance of the machine. They've also added a lightweight skid plate, produced in plastic resin, also designed to protect the frame, water pump, hoses and engine cases. It will also tackle dirt and mud ingress. Improved handling Helping to keep the bike in a straight line is new suspension at the front and rear, with 1mm wider 25mm KYB fork tubes based on the YZ250F, complete with enduro-specific settings. To the rear, the bike gets a YZ250F-derived shock, with a stronger and lighter coil spring saving a further 350g. New technology To help control power delivery, Yamaha have also equipped the WR with a handle bar-mounted dual engine map switch, allowing you to swap between two factory modes. Maps can also be customised to rider preference within the Power Tuner app, before being uploaded to the bike's Communication Control Unit. With 16 adjustable values available for fuel injection, and ignition timing alongside three factory base set-ups, the app also features a race log, engine diagnostics and the ability to share information with other riders. VIDEO :
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