| Harley-Davidson Baja 100 | |
| Manufacturer: | Aermacchi |
| Production: | 1969–1972 (model years 1970–1973) |
| Assembly: | Varese, Italy |
| Class: | Off-road |
| Engine: | 982NaN2 2-stroke single |
| Bore Stroke: | 50× |
| Compression: | 9.5:1 |
| Power: | 12.6bhp @ 8,000 rpm |
| Transmission: | 5 speed |
| Tires: | Metzeler front: 3.00 × 21, rear: 3.50 × 18 |
| Wheelbase: | 52inches |
| Length: | 78.5inches |
| Width: | 34inches |
| Dry Weight: | 185lbs |
| Fuel Capacity: | 2.5USgal, including 12NaN2 reserve. |
The Harley-Davidson Baja 100 was a small displacement off-road motorcycle made for Harley-Davidson in Italy by Aermacchi, which was 50% owned by Harley-Davidson at the time. It was one of Harley-Davidson's attempts to enter the small displacement off-road motorcycle market. It was built in Aermacchi's Varese, Italy factory.
It had a 98cc two-stroke, single cylinder engine with five speed transmission, derived from the current two-stroke production, mostly Aletta and Aletta d'Oro off the shelf parts by reducing bore from 56 mm to 50 mm.
The only purpose-made part was the frame to accommodate for the front holder for the cylinder head and the air filter box.
The first production run started in September 1969 and ended just before August, traditionally the time of the year when factories were closed for holidays and consequently a new model year introduced.
Production runs of 1973 are not known even if some MY 74 models seem to exist but this means that there have been no changes after MY73.
As a rule frame numbers (which are repeated on the engine) start with 8B on the MSR (Competition Model) and 8C for the "street model" which had lights, muffler and a high front fender. But for some early "street models" the MSR frame numbering may apply.
A major overhaul took place end of 1972 when the engine was fitted with a new aluminum cylinder and carburetor, and gear shift on the right side of the engine. There were other minor differences such as the rear fork or the missing vent on the tank.
The Baja had a racing history and won the Baja 1000 in 1971 with the official Harley-Davidson team in its class. In that race Harley entered some 14 Baja models, of which 8 finished in the top 10, including the race winner.