Harley Davidson: Hogs in the Dirt
Until the late 1960's, there really was no such thing as a dirt bike. People just rode whatever bike they wanted to, no matter if the road was paved or a vast untouched desert. If you want to keep riding when the pavement ends, even today there is no reason you can't keep riding a Harley Davidson.
This article applies to the Harley Davidson in general.
Way back when, in the days before the Japanese bike invasion, there was no such thing as a dirt bike. There were tires that got better grip in the dirt, and there were modifications that could be done to make a bike better for use on unpaved surfaces, but there wasn’t really any dedicated off-road bikes. That all started to change in the 1960's, when the British bike makers introduced more dedicated competition scramblers. Next, the German, Spanish and Swedish companies like Maico, Bulltaco, and Husqavarna revolutionized off-road riding with their light and powerful 2-stroke bikes. Harley Davidson even tried to get in on it by converting some of their smaller displacement Italian Aermacchi models into enduro and motocross machines. When the dust literally settled though, on the dirt ovals there was still no one who could make a bike competitive with the mighty Harley Davidson XR750 flat track bike, until recently.
1970's Small Bore Competition Bikes
Harley’s first attempt at a dedicated dirt bike was the Baja 100 in 1971, aimed right at the heart of Hodaka, Honda, and the rest of the Johnny come lately Asian imports. Unfortunately, a good deal of its powertrain started life as the M50/M65 moped some years ago, and the 10 to 12hp they claimed was likely measured directly at the advertising copy writer’s pen. Even though specially built factory machines managed to win the 100cc class at the Baja 1,000 that year, Harley Davidson only managed to sell about 5,000 units in the entire five year run.
In 1974, new corporate bosses AMF encouraged Harley to try again and build a bike that could compete in the 250cc motocross classes, which had exploded in popularity. Less than 100 competition machines were built, but they were not competitive in AMA motocross. In 1978, however, they did make the mass market MX250. While power was very competitive at the time, there were teething issue with the chassis. Harley did score 1 AMA national MX win that year though, then promptly disbanded the team, stopped selling the bike, and in fact sold off the rest of Aermacchi to Cagiva. In all, only about 1,000 of these bikes were ever made.
Figure 3. 1974 Harley 250 motocross bike with unique rear fork suspension. 
Figure 4. The rare 1978 Harley Davidson MX250 competition bike.
Dual Sport and Military Bikes
Harley made plenty of other bikes in the 1970's that had some dirt focus, but these weren't race bikes. There was a scrambler version of the 350cc 4-stroke single, called the SX350, and there was the 2-stroke dual sport SX250 as well. In the smaller classes, there was the SX175 and SX125, and earlier the Rapido.
Figure 5. Harley Davidson SX350 Scrambler. 
Figure 6. Harley Davidson SX250. 
Figure 7. Harley Davidson SX175. 
Figure 8. Harley Davidson Rapido SX125.
There were also 90cc playbikes called the Z90, and X90 as well as minibikes called the Shortster in 90cc or 65cc sizeswere similar to the Honda Trail 70 and Minitrail.
Figure 9. Bad News Bears Harley Davidson Z90. 
Figure 10. Harley Davidson Shortster.
It should also be mentioned that from 1987 to 2000 Harley Davidson has also built a Rotax powered dirt bike called the MT500 or MT350E for the military, mostly in Europe. You seldom find them in the US, but they do occasionally come up, and the Rotax motor is very similar to that used in a lot of other bikes, like the ATK, so they are not hard to keep running.
Off-Road Sportsters
If you spend any amount of time with Harley riders, you’ll know that for many of them it is like a religion and there is no way they’d consider riding a Honda, even in the desert or the woods. Many of these diehards, and a few certified crazy people, have converted Sportsters into off-road bikes, with varying degrees of success. It does make some kind of sense, the Sportster is the smallest and lightest Harley available, and beat up 883 models are fairly cheap after being ridden hard by their first few owners. What does it take to take a Sportster off-road, besides bravery? A set of knobby dual sport tires, stock or longer rear shocks, high pipes, mid controls, and a low wide handlebar with a crossbar is all it takes to get started. If you get serious, you may want to convert over to a chain instead of a belt, because the belt can get shredded if you trap a rock in it.
Figure 12. Sportster for off-road riding. 
Figure 13. This Sportster rode the entire Al-Can highway.
Of course, you are never going to be taking a Sportster off a table top, double, or triple jump, so you might as well make it more of a street tracker. Who really needs all that ground clearance when you just want to have some fun sliding around on fire roads?
Related Discussions
- Harley MT500 - HDForums.com
- Dual Sport Tires on a Sportster - HDForums.com
- Off-road Sporty - HDForums.com
- Sportster Conversion to Street Tracker - HDForums.com
- Street Tracker Mods - HDForums.com
- Street Tracker Build - HDForums.com
