Tough single takes XT into the future

Published: 02 September 2003

YAMAHA has replaced its air-cooled XT600E with a rugged new liquid-cooled machine with more power, up-to-the-minute styling and sharpened handling.

The XT660-R becomes the latest in a long line of XTs which can trace their roots back to the mid-’70s. Now the XT name will keep going well into the 21st century.

The extra performance – about 10 per cent more bhp than the old air-cooled bike – comes courtesy of a 659cc single-cylinder motor that Yamaha claims is all-new – although owners of the XTZ660 Tenere which dates back to 1993 might find the general appearance and spec of the motor familiar. The two engines have similar crankcases and share the same bore and stroke dimensions of 100mm x 84mm.

But the latest XT’s cylinder head is all-new and houses four valves instead of the five of the old XTZ, all actuated by a single overhead camshaft.

The new XT also has a new fuel-injection system – a first on a Yamaha single-cylinder machine – and incorporates an automatic decompressor for easier starting. It produces a claimed peak power figure of 48bhp at 6000rpm and peak torque of 43ftlb at 5250rpm.

Unlike previous Yamaha XTs, the new 660’s frame features twin upper rails compared to the old bike’s single spine, which the firm claims increases rigidity, high-speed stability and handling. By using the engine as a stressed chassis member, Yamaha has managed to add the spar without increasing the weight of the chassis. The XT660-R’s overall mass is 165kg (363lb).

The twin rail frame design also incorporates the engine’s oil tank, which is positioned just behind the headstock where Yamaha claims airflow around the bike will help keep it cool.

Paioli supplies the 43mm forks, while there is a single shock at the back which is adjustable for pre-load.

Braking, courtesy of a 298mm front disc squeezed by a two-piston Brembo caliper with a 245mm rear disc and single-pot caliper, should be enough for the lightweight machine’s relatively modest performance.

No prices for the Italian-built machine have yet been announced, but it is expected to go on sale early next year at around the £4000 mark.