Yamaha YDS7 (1972)

The Yamaha YDS-7 is a motorcycle model that was produced in 1972. It has a two-stroke, piston-port, parallel twin engine with a capacity of 247 cc (15.0 cu-in) and a bore x stroke of 54 x 54 mm. The compression ratio is 7.5:1 and it is air-cooled with induction coming from a 26mm Mikuni carburetor. It is powered by a Mitsubishi contact breaker ignition and has a kick start. The maximum power output is 30 hp at 7500 rpm and maximum torque is 21 ftlb at 7000 rpm. The clutch is a wet, multi-plate clutch mounted on the left side of the crankshaft and it has a 5-speed helical-gear primary drive transmission. The final drive is a chain and the front suspension is a 34mm telescopic fork while the rear is twin shock. The front brakes are 180mm twin leading shoe drum and the rear brakes are 180mm single leading shoe. The front tire is a 300 x 18 and the rear tire is 3.25 x 18. The wheelbase is 1300 mm (51.1 in) and the wet weight is 145 kg (320 lbs). The fuel capacity is 11.4 litres (3.0 gal). At 30 mph in top gear, the engine rpm is around 2,500.

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Technical specifications:

Make Model: Yamaha YDS-7

Year: 1972

Engine: Two stroke, piston-port, parallel twin

Capacity: 247 cc / 15.0 cu-in

Bore x Stroke: 54 x 54 mm

Compression Ratio: 7.5;1

Cooling System: Air-cooled

Induction: 26mm Mikuni

Ignition: Mitsubishi contact breaker

Starting: Kick

Max Power: 30 hp @7500 rpm

Max Torque: 21 ftlb @ 7000 rpm

Clutch: Wet, multi-plate clutch mounted on left side of crankshaft

Transmission: 5 Speed Helical-gear primary drive. Rear chain % x %in with top guard. Engine rpm at 30 mph in top gear, approximately 2,500.

Final Drive: Chain

Front Suspension: 34mm Telescopic forks

Rear Suspension: Twin shock

Front Brakes: 180mm twin leading shoe drum

Rear Brakes: 180mm single leading shoe

Front Tyre: 300 x 18

Rear Tyre: 3.25 x 18

Wheelbase: 1300 mm / 51.1 in

Wet Weight: 145 kg / 320 lbs

Fuel Capacity: 11.4 Litres / 3.0 gal