The Yamaha YDS7 is a motorcycle produced in 1966-67 with a two-stroke, 247cc parallel twin engine. It has a compression ratio of 7.5:1 and is air-cooled with two Mikuni VM24SC carburetors. The electrical system includes a Mitsubishi 65-watt dc generator, six-volt battery, and coil ignition. The YDS7 has a maximum power of 24 hp at 7500 rpm and a maximum torque of 18.1 ft-lb at 7500 rpm. The clutch is wet and mounted on the left side of the crankshaft, and it has a 5-speed transmission with a top gear engine rpm of around 2500 at 30 mph. The front suspension includes telescopic forks with hydraulic damping, while the rear suspension consists of dual shocks and a pivoted rear fork controlled by spring-and-hydraulic units with three-position load adjustment. The YDS7 has drum brakes both in the front and rear and runs on 3.00-18 front and 3.25-18 rear tires. Its dimensions are 2006mm x 792.5mm x 1066.8mm, with a wheelbase of 1470.5mm and a wet weight of 145kg. Its fuel capacity is 11.4 liters.
Technical specifications:
Make Model: Yamaha YDS-3C
| Year | 1966-67 |
|---|---|
| Engine | Two stroke, piston-port, parallel twin, Crankshaft supported in four roller bearings; needle-roller small-end and big-end bearings. Light-alloy cylinder head; |
| Capacity | 247 cc / 15.0 cu-in |
| Bore x Stroke | 56 x 50 mm |
| Compression Ratio | 7.5;1 |
| Cooling System | Air-cooled |
| Induction | 2x Mikunis VM24SC with air filter. Direct-operating, coupled air slides. |
| Ignition | Generator |
| Starting | Kick |
| Electrical Equipment | : Mitsubishi 65-watt dc generator charging six-volt battery through automatic voltage regulator. Coil ignition. 6in-diameter headlamp with pre-focus light unit; 35/35-watt main bulb. |
| Max Power | 24 hp @ 7500 rpm |
| Max Torque | 18.1 ft-lb 4.2 kgf-m @ 7500 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 |
| Gear Ratio | 1st 2.545 2nd 1.533 3rd 1.167 4th 0.950 5th .0773 |
| Front Suspension | Telescopic forks with hydraulic damping. |
| Rear Suspension | Dual shocks swinging arm, Pivoted rear fork controlled by spring-and-hydraulic units with three-position adjustment for load. |
| Front Brakes | Drum |
| Rear Brakes | Drum |
| Front Tyre | 3.00 -18 |
| Rear Tyre | 3.25 -18 |
| Dimensions | Length 2006 mm / 79 in Width 792.5 mm / 31.2 in Height 1066.8 mm / 42 in |
| Wheelbase | 1470.5 mm / 51.9 in |
| Wet Weight | 145 kg / 320 lbs |
| Fuel Capacity | 11.4 Litres / 3.0 gal |
