What began as back room tinkering at Honda in the late 1960’s became a product now representing over 30% of many motorcycle dealers’ unit sales. Honda dealers asked for a new product that would offer sales in the winter season, a time when sales were off in the northern United States. This original Honda US90, a three-wheeler with a flotation tire and wheel* design then used on some American made six-wheel machines, was the answer.
Originally dubbed the US90 due to America being its first market, the machine soon became the ATC90; the All Terrain Cycle. It borrowed the engine/ transmission unit from a Honda Trail 90, an 89cc OHC single with a dual range transmission, but used rope starting. The frame was pressed steel with rigid tubular forks and a live rear axle also with no suspension. The cushy tires absorbed a lot of surfaces irregularities and was easier on trails than knobbies. Where most bodywork on today’s ATVs is polypropylene, the ATC90 used a steel fuel tank and front fender and a fragile fiberglass seat/fender unit. Summer Yellow, Bright Red, Aquarius Blue and Parrot Green were sporty new color offerings; it was the 70’s.

In desert and rural areas the ATC90 was a hit; urban Honda shops sold fewer. Honda got enough patents that the other OEMs had difficulty competing unless they bought rights, which some did. But what appeared to be a stable machine invited young and unskilled operators who often got into trouble. The solid rear axle called for a lean to the outside to turn at low speeds, the under 40 inch wheelbase made wheelies come easily. Injuries started to rack up, as did lawsuits against Honda, hundreds of millions in lawsuits eventually, and the CPSC stepped in and banned three-wheelers.
But more stable four-wheeled ATV designs were already on the drawing boards of half a dozen manufacturers and even wider audiences were found in racing, agriculture, emergency, hunting, oil field service and more. What was a $600 plaything in 1970 is now a key piece of transport worldwide and has likely taken a big bite out of small tractor, golf cart and off-road motorcycle sales. Just about everywhere you look, a modern ATV is at work, or play, with some high performance and four passenger units topping $20,000.

This Honda ATC90 is part of the DIRT RIDING USA exhibit presented by J&P Cycles, and is one of only two ATVs in the entire National Motorcycle Museum. Take in almost 50 dirt bikes from Europe, England, Japan and America when you visit plus over 450 other motorcycles of all types, 1899 to present.
*If a tire puncture occurred on the early ATC90, the entire wheel tire unit might need replaced. In 1982 the retail price was $230, then about three to four times the price of a 4.00 x 18 motorcycle tire! Cheaper demountable tire designs came in 1975.


  • Engine: 4-Stroke, Air-Cooled
  • Bore & Stroke: 50mm x 45.6mm
  • Displacement: 89.5cc
  • Compression Ratio: 7.5 : 1
  • Carburetor: 16mm Keihin
  • Primary: Gear Driven
  • Clutch: Semi-Automatic
  • Transmission: 4-Speed / Dual Range
  • Final Drive: Chain
  • Starting: Recoil Rope
  • Wheelbase: 39.8 Inches
  • Suspension: Rigid
  • Wheels/Tires: 22 x 11 x 3.5 Inches/ 2PSI
  • Brakes: Drum, Rear Only
  • Weight: 197 Pounds
23 replies
  1. Tom Hamilton
    Tom Hamilton says:

    I had a childhood friend who lost his life on this very machine in 1973. I’ll say it again now like I did then——-those wheels are essentially balloons……….do the math.

  2. joseph a way
    joseph a way says:

    This thing is far from museum quality. seat worn, tires warn and over inflated, terrible looking fuel lines and filters, rusty grab bar, i can go on and on. two thumbs down.

  3. Mark
    Mark says:


    Thanks for posting a comment regarding the ATC90. The National Motorcycle Museum has high regard for original unrestored/preserved motorcycles. Probably only 35% of the bikes on display are concours quality restorations. The rest range in condition from older restoration, excellent original all the way to barn fresh in the Barn Find exhibit. “Museum Quality” not not always mean flawless/like new as you might see in a fine arts museum showing paintings, sculpture, furniture that shows the wear of its lifetime, possibly repairs, yet is totally acceptable for display.

    Most ATC90’s, or US90s, the early ones like this, have been scrapped. For one thing, the tires, which are a unit with the hub, are no longer available (true OHTSUs) from Honda, and the last time I saw a rear tire for sale (new) it was $2500. Seriously. So worn tires are often as close as you can get to ORIGINAL tires. As for the grab rail, the scuffs show our visitors that this particular machine may have been flipped upright by its rider, and hit the grab bar. This is actually a later/longer grab rail that extends back to lessen the likelihood of a complete flip over. More important, it might remind those who rode this machine of its characteristics, and why 3-wheelers were banned eventually.

    Yes there’s a bit of wear and tear, and wrong fuel lines, but finding an original ATC90 this original is tough and we wanted to treat our visitors to one, bring back their memories, or help them explain to their kids just what the first “ATVs” looked like.

  4. lonnie cobb
    lonnie cobb says:

    I got a new green one in 1973, love the us 90s.I never got hurt on mine,maybe i was just lucky.anyway yes i still have it,with the balloon tires.

  5. Darryl
    Darryl says:

    I Live in Australia and have a brand new rear axle I bought new in 1973 and also the axle housing mount
    Can any one let me know what it would be worth?

  6. Alex Rakow
    Alex Rakow says:

    I currently just acquired a 72 US90 that’s 100% original. Guy rode it to the local apple orchard and back and then put it in his house until I finally took it off my hands. Came with the original manual, brochure. The bike still has the tape over the pull start cord handle and is in brand new condition

  7. Troy Adams
    Troy Adams says:

    I have two US 90s for sale. One is a 1970 yellow with three balloon tires two of which you do not hold air. The other is a 1972 green the front and back hold air but one back tire is rotten. When I say hold there, I mean you can blow it up and it will last for about three days so no none of the tires are actually good but these machines are, 100% original unmolested and in great shape, Considering the age, obviously, One needs a seat cover, and they both need to be freshened up. If anybody is interested in purchasing these, please email me.

    • jon brundrett
      jon brundrett says:

      Hey Troy!
      I just ran across this and curious if you still have the US 90s? Feel free to email me back. I’m located in Iowa. Thanks so much


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