The Bulletproof Little Honda ST90 “Sport Trail”

Honda ST90

The Honda ST90 was one of the most desirable motorcycles in the world when it was released in 1973, that is if you were a 10-14 year old with dreams of a career in the upper echelons of motocross competition.

The ST90 was essentially a more off-road focussed version of the popular CT90, a stamped steel backbone frame motorcycle that remains one of Honda’s hidden success stories. The ruggedized ST90 version didn’t sell particularly well and it was pulled from production after just two years.

Fast Facts – The Honda ST90 “Sport Trail”

  • Honda naming conventions for their motorcycles (and trikes) were all over the place in the 1960s and early 1970s. As a result the ST90, which was a member of the CT model family, didn’t have a CT name.
  • The “ST” in ST90 stands for “Sport Trail,” this was a mid-way motorcycle between minibikes and full size enduro mounts targeted at both adults and kids. Many adults ended up loving them due to their low weight and easy to use automatic clutches and gearboxes.
  • Honda was a dominant force in the world of minibikes (monkey bikes), mid-sized motorcycles, and off-road trikes in the early 1970s.
  • The ST90 was ultimately a failure for Honda, it sold in relatively low numbers as it wasn’t differentiated enough from other quite similar models. That said, those who own them typically love them and extol their virtues.

The Honda CT Series

The Honda CT series entered production in 1964, it would go on to become one of the Japanese marque’s most enduringly popular lines of motorcycles.

Honda CT90

Image DescriptionThis is the Honda CT90, it was marketed to off road enthusiasts and outdoorspeople who frequently used them for hunting, fishing, and exploring. Image courtesy of Honda.

The name “CT” is believed to stand for “Cub Trail,” as the model series was essentially developed as a dual sport version of the popular Honda Super Cub – in motorcycle terminology “dual sport” simply means a motorcycle is designed to be ridden both on and off road.

Honda has produced a vast array of different CT models over the years, from the smaller CT70 through the more common CT90 and CT110, all the way up to the larger CT250S Silk Road.

It’s important to note that many of the motorcycles in the CT family were aimed at younger, less experienced riders. Most had centrifugal clutches and automatic transmissions which significantly lowered the barrier to entry.

Other models like the CT110 were ridden mostly by adults, in Australia this model became famous as the “Postie Bike” due to the fact that they were ridden by postal workers while delivering the mail – rain, hail, or shine.

The Honda ST90

Although it’s not named as a member of the CT family, the ST is very closely related to the series and has many interchangeable parts with them. Like many of the CT bikes the ST90 has a stamped steel backbone chassis, an under-slung air-cooled engine, an upright riding position, and dual sport credentials.

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Image DescriptionIn some respects the Honda ST90 is a scrambler, it’s road legal and it can be driven on or off road, and it has more off road capability than its sibling, the CT90.

Unlike its sibling the CT90, the ST90 was developed with more focus on off road riding. It has engine protection cradles, more ground clearance, and higher front and rear fenders.

Honda introduced the ST90 in 1973 and sold it until 1975, interest wasn’t as strong as was hoped and as such the model was discontinued. Due to this short production run there are far fewer ST90s than CT90s in the world, and as a result they’re becoming quite collectible.

Honda ST90 Specifications

  • The Honda ST90 is powered by a single-cylinder, air-cooled 89cc engine with a single overhead cam operating two valves.
  • Power is sent to a three-speed semi-automatic transmission through a centrifugal clutch, then on to the rear wheel by way of a chain final drive.
  • Suspension consists of traditional hydraulic forks up front with dual shock absorbers in the rear, and the ST90 is fitted with “knobby” tires front and back optimized for off road use.
  • The ST90 has twin engine protection bars, a rear luggage rack, off road style elevated front and rear fenders, and high handlebars.
  • The very low weight combined with good ground clearance and excellent reliability have made the ST90 popular as an inexpensive, entry-level trail bike.
Honda ST90 6

Image DescriptionPower is provided by an 89c single-cylinder engine with a single overhead cam operating two valves. It has a three-speed semi-automatic transmission and power is sent to the rear wheel via a traditional chain drive.

The 1973 Honda ST90 Shown Here

The bike you see here is a Honda ST90 from 1973, it’s said to have spent the better part of 30 years in storage before it was bought by the current owner in 2022.

After getting it home the new owner cleaned the carburetor, changed the oil, and replaced the battery, spark plug, and fuel filter.

It’s now being offered for sale with a tool kit, an owner’s manual, registration documents from previous ownership, a copy of the original owner’s title, and a clean California title in the seller’s name.

If you’d like to read more about this unusual trail bike you can visit the listing here on Bring A Trailer.

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Images courtesy of Bring A Trailer

Honda ST90