Yamaha AT1
The Yamaha AT1 is a single cylinder enduro motorcycle produced by Yamaha Motor Company from 1969 to 1971. It was part of Yamaha's early efforts to expand their motorcycle lineup and enter the growing off-road market.
Specifications +Yamaha AT1 Specifications Attribute Value Engine 123cc, 2-stroke petrol Bore × Stroke 56 mm × 50 mm Top speed 60 mph (97 km/h) plus Power 11.5 BHP at 7,500 rpm Torque 8.5 ft-lb at 6,000 rpm Transmission Wet, multiple disc Suspension Front: Telescopic fork, Rear: Swinging arm Brakes Internal expansion Wheelbase 50.6 in (1,290 mm) Dimensions L: 77.2 in (1,960 mm)W: 35.8 in (910 mm)H: 42.9 in (1,090 mm) Weight 218 lb (99 kg) (dry)234 lb (106 kg) (wet) Fuel capacity 1.9 US gal (7.2 L; 1.6 imp gal) Fuel consumption 141.1 mpg‑US (1.667 L/100 km; 169.5 mpg‑imp) at 25 mph
Models and Versions The Yamaha AT1 was available in three different models, each corresponding to the year of production:
1969 Yamaha AT1 1970 Yamaha AT1B 1971 Yamaha AT1C
Each year, the AT1 was also available in the Motocross edition designated by an M. The M models were very similar to the regular models other than a few performance-enhancing features, such as weight reduction, higher compression ratio, tuned exhaust, larger carburettor with 26 mm throttle bore, and tuned gearing ratio.
Technical Specifications +Additional Technical Specifications Specification Value Compression ratio 7.1:1 Lubrication System Yamaha Autolube Starting system Electric for Enduro Versions and kick starter Carburettor VM24SH Battery 12V 7AH Ignition system Battery ignition
Model History and Frame Numbers +Model History and Frame Numbers Model Year Color Frame Numbers AT1 1969 Pearl White AT1-100101 to AT1-119829 AT1M 1969 Pearl White (MX Version) AT1-300101 to AT1-303790 AT1B 1970 Competition Yellow AT1-119830 to AT1-144709 AT1C 1971 Competition Yellow AT1-144710 to AT1-170509
Parts and Maintenance Some parts, such as fuel tanks, were interchangeable between the AT1 and other Yamaha models of the same era, like the CT1. Yamaha has continued to support these vintage models by producing replacement parts, such as petcocks, which fit the 1969-1971 AT1 models.
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