Two-Stroke SuMo Conversion – 1975 Yamaha DT400 Custom

In Japan, Less than 5k, Sport by Tim HuberLeave a Comment

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In 1968, Yamaha introduced the 250cc DT1, a 22hp two-stroke enduro wrapped in a double-loop cradle frame. The DT was something of an instant hit, and the Tuning Fork company followed it up with the introduction of the 125cc AT1, as well as the larger 360cc RT1 in 1970. By ’75 Yamaha had bored out the RT1’s single to 397cc’s, and thus, the iconic DT400 was born.

The DT-1 was reportedly good for 24 horses at 5,500 rpm and an even 24 ft-lbs of torque at the 5,000 rpm mark, all
while tipping the scales at under 300 pounds. The DT1’s reception from journalists was almost universally positive, however it failed to be the commercial success its manufacturer had anticipated, with the punchy engine being more suited for competition use than it was simple treks from point A to B.

So as emissions regulations tightened, Yamaha became increasingly focused on its TT/XT range — first released in ’76. The DT did receive
minor upgrades such as a monoshocked rear suspension setup in ’77, just a few years before the plug was pulled on the two-stroker in ’79 so Yamaha could focus its efforts on its four-stroke offerings. For a more in-depth look at the DT400, we recommend checking out this retrospective from our pals at Rider Magazine.

This particular first-year DT400 example has supposedly undergone a recent and extensive restoration including a complete engine rebuild using a Mikuni flat slide carb and upgraded internals. The stock suspenders were binned to make room for Progressive rear shocks and the front end (and brakes) from a TW200. With the mechanics and suspension all sorted, the owner then went on to transform the classic enduro into a bonafide supermoto machine using a sumo fender, RaceTech fork emulators, Acerbis handguards, custom handlebar pad, rear spools, and 17” Buchanan rims shod in sticky street rubber. The seller claims this Yammy Sumo now sports over $6,000 in aftermarket goodies, and that only 83 miles have been put on it since the rebuild.

You can find this custom 1975 Yamaha DT400 SuperMoto conversion for sale here on Craigslist in Redondo Beach, California with a price of $4,750.

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