Engineering:Yamaha AT1
Yamaha AT1
The Yamaha AT1 is a single cylinder enduro motorcycle produced by Yamaha Motor Company from 1969 to 1971.[1] It was part of Yamaha's early efforts to expand their motorcycle lineup and enter the growing off-road market.
Specifications
| Attribute | Value |
|---|---|
| Engine | 123cc, 2-stroke petrol[1] |
| Bore × Stroke | 56 mm × 50 mm[1] |
| Top speed | 60 mph (97 km/h) plus[1] |
| Power | 11.5 BHP at 7,500 rpm[1] |
| Torque | 8.5 ft-lb at 6,000 rpm[1] |
| Transmission | Wet, multiple disc[1] |
| Suspension | Front: Telescopic fork, Rear: Swinging arm[1] |
| Brakes | Internal expansion[1] |
| Wheelbase | 50.6 in (1,290 mm)[1] |
| Dimensions | L: 77.2 in (1,960 mm) W: 35.8 in (910 mm) H: 42.9 in (1,090 mm)[1] |
| Weight | 218 lb (99 kg) (dry) 234 lb (106 kg) (wet)[1] |
| Fuel capacity | 1.9 US gal (7.2 L; 1.6 imp gal)[1] |
| Fuel consumption | 141.1 mpg‑US (1.667 L/100 km; 169.5 mpg‑imp) at 25 mph[1] |
Models and Versions
The Yamaha AT1 was available in three different models, each corresponding to the year of production:[1]
- 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.[1]
Technical Specifications
| Specification | Value |
|---|---|
| Compression ratio | 7.1:1[1] |
| Lubrication System | Yamaha Autolube[1] |
| Starting system | Electric for Enduro Versions and kick starter[1] |
| Carburettor | VM24SH[1] |
| Battery | 12V 7AH[2] |
| Ignition system | Battery ignition[1] |
Model History and Frame Numbers
| Model | Year | Color | Frame Numbers |
|---|---|---|---|
| AT1 | 1969 | Pearl White | AT1-100101 to AT1-119829[1] |
| AT1M | 1969 | Pearl White (MX Version) | AT1-300101 to AT1-303790[1] |
| AT1B | 1970 | Competition Yellow | AT1-119830 to AT1-144709[1] |
| AT1C | 1971 | Competition Yellow | AT1-144710 to AT1-170509[1] |
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.[3] Yamaha has continued to support these vintage models by producing replacement parts, such as petcocks, which fit the 1969-1971 AT1 models.[4]
References
- ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23 1.24 "69-71 AT1 125 Specifications". https://yamaha-enduros.com/index.php/125cc-specs/46-69-71-at1-125-specifications.
- ↑ "Yamaha AT1C 125 Enduro Battery Replacement (1969-1971)". https://www.techbatterysolutions.com/yamaha-at1c-125-enduro-battery-replacement-1969-1971/.
- ↑ "1969 - 1971 AT1 & CT1 Fuel Tanks Same Size?". 2021-09-17. https://yamaha-enduros.com/index.php/forum/1968-71-badge-bikes/16132-1969-1971-at1-ct1-fuel-tanks-same-size.
- ↑ "Brand New Yamaha Petcocks for our bikes!". 2014-06-06. https://www.yamaha-enduros.com/index.php/forums/performance-improvements/164-brand-new-yamaha-petcocks-for-our-bikes.
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