This is from the site Bring a Trailer (https://bringatrailer.com/) ...
This 1978 Husqvarna 390 Automatic was purchased by the seller from its original owner two years ago. Bought as a pair, this one’s been restored, with attention spent on mechanicals as well as cosmetics, though it sounds to have been little used from the start, the seller speculating only 15 hours of riding time prior to being put into dry storage in 1980. These bikes have a very interesting back story involving the Swedish army, as well as some equally fascinating engineering–the 4-speed gearbox’s unusual but elegant inner workings for example, as well as the fact that its fitted in a full-race frame. Find this one here on eBay in Huntington Beach, California with a $7,500 BIN.
Reads the meat of the ad: “Purchased from original owner in 2014. Bike has been completely worked on and tuned by Uptite Husky in Santa Ana, California. Runs as new, race-ready. Totally restored, frame and swing arm powder coated, exhaust ceramic coated. All new NOS clutch shoes, springs and related parts in transmission. New tires. Original paint on tank. Original seat. Has been in dry storage since 1980. I bought two of these from the original owner, who purchased this one for his wife in 1979. She may not have had 15 hours on the bike. She failed to allow it to idle before engaging the transmission. That’s why I needed to replace the 1st gear clutch parts with NOS parts. I did not restore the wheels, as new buyer may choose to ride in vintage events. I will include an extra green tank, original owner’s manual, and a California pink slip. A Husky speedometer will be installed.”
According to this very interesting link, Husky originally developed these bikes in response to a request from the Swedish military, which required soldiers to be trained and fully adept at Enduro-style riding in as little as one week, the idea apparently being that once freed from having to manipulate a clutch and gearbox, green riders could instead focus on balance, weight transfer, and other riding techniques.
From the above link: “Most of the bike was a direct lift from existing Huskys. This included the reed-valved, single-cylinder two-stroke engine and all the chassis. Only the gearbox was unique to the Auto and this fitted inside a regular Husky engine case. The heart of the gearbox was the clutch mechanism. Initially, drive was taken up by a centrifugal clutch, and then a series of a dog clutches engaged sequentially locating higher gears.”
They continue: “It was brilliantly simple and even more brilliantly effective with bomb-proof reliability and faultless changes even under full power.” The article’s writer goes on to speculate that sales were ultimately hurt by the lack of engine braking and very slightly slower performance, largely thanks to four gears rather than the six in conventional Husky race bikes of the time.