Honda CB 250RS

   

Make Model

Honda CB 250RS

Year

1980-81

Engine

Air cooled, four stroke, single cylinder, SOHC, 4 valve

Capacity

249
Bore x Stroke 74 x 57.8 mm
Compression Ratio 9.3:1

Induction

30mm Keihin

Ignition  /  Starting

  /  kick

Max Power

11.6 hp @ 8500 rpm

Max Torque

12.6 Nm @ 8000 rpm

Transmission  /  Drive

5 Speed  /  chain

Front Suspension

Telescopic forks, 120mm wheel travel

Rear Suspension

Dual shock with adjustable preload, 90mm wheel travel

Front Brakes

Single 250mm disc

Rear Brakes

140 drum

Front Tyre

3.00-18

Rear Tyre

4.10-19

Dry Weight

136 kg

Fuel Capacity 

14 Litres

Consumption  average

25 km/lit

Standing ¼ Mile  

16.3 sec

Top Speed

136 km/h

Fashion moves in circles in the motor cycling world: the single-cylinder, a staple offering pre-1960 from leading manufacturers, has been resurrected in recent years by the Japanese, who once had little time for anything less complicated than an ohc, preferably dohc, twin.

Honda with their XL trail bikes of the 1970s were the first of the Big Four to market an overhead-valve single in the West. In 1980 they repeated, probably unwittingly, a precedent laid down a half-century earlier by British manufacturers, who were then in the habit of dressing up their singles with twin exhaust ports, pipes and silencers.

The XL250 had twin ports, and pipes, but only one silencer: what Honda did, when it came to making an RS out of an XL, was to lead the pipes into separate silencers with 'megaphone' outlets, treat the engine and cases to a matt-black finish, and make use of a low, light frame. The result, the keenly priced CB250RS, was a considerable success in its first two years and looked set to be an even better seller in 1982, when it acquired an electric starter.

Honda's single, having a four-valve layout, was a reasonable candidate for double exhausts; with one valve per pipe, there was even some technical merit in the arrangement, whereas the pre-war British single usually had but one exhaust valve, and thus changing to twin ports was on the whole a purely cosmetic improvement.

The RS engine was fitted with counter-rotating weights, driven by chain, to dampen vibration, an automatic chain-tensioner, and a larger carburettor (compared with the XL), at 30mm instead of 28mm.

With aluminium but wire-spoked wheels and a front disc brake, and weighing no more than 300 lb, the RS handled well and had a surprising turn of speed — to beyond 90mph in favourable conditions. Ironically, riding it recalled for anybody with the relevant experience one of those BSA-group 250s summarily brushed aside by the all-conquering Japanese in the 1960s.