Seeing a Honda ATC 70 race across dirt roads brings back the thrill of yesteryears. Back in the day, kids did not need fancy tech to explore the outdoors. Flotation tires and a robust engine were plenty enough to boost rider confidence in climbing over rocks and traversing light snow. A change in terrain? All it took were paddle tires with chevron-type cleats, and the vehicle would be ready for wading through sand and mud.
The Honda ATC 70 was the first off-road vehicle for kids to carry the All-Terrain Cycle (ATC) trademark. Featuring a 4-speed transmission and semi-automatic clutch, flotation tires, foot guards, and easy-to-operate brakes, the Little Red was the perfect trike for youngsters and adults.
Single-handedly spawning the manufacture of youth three-wheelers is not the only thing that makes the Honda ACT 70 a standout. Its updated body styling and incredible power-to-weight ratio make it an excellent family vehicle and pit bike – small but powerful enough for both kids and youngsters at heart. Stick around, and let this guide take you on a journey through the specifications, enhancements, and history of this well-loved red trike.
History of the Little Red
The successor to the ground-breaking US90, the Honda ATC 70 was produced from 1972 to 1984 for the ’73-’85 models. Although it was technically the second all-terrain cycle produced by Honda, it was the first off-road vehicle to carry the ATC trademark, which the company acquired recently before its launch. This small three-wheeler was built by Honda engineers with kids in mind and initially released as a 72-cc trike. In the years that followed, these three-wheelers developed to include engines going from 70- to over 200-cc.
During its 12-year production run, the trike temporarily went on hiatus, during which time Honda further developed the ATC 70’s body styling, engine, and drivetrain. These refinements were implemented in two installments – first in 1978 and second in 1982. However, these developments were not enough to stop the perils that came with riding ATCs, which by then had earned them the infamous moniker “Three Wheels of Death.” The ATC70, like any other trike, was accident-prone and unideal for riding on uneven terrain. Plus, the absence of a mechanical suspension only made things worse for the vehicle. At this rate, outlawing the three-wheelers was inevitable.
Check out this video by Kaplan America showing off a rebuilt Honda ATC 70:
Improvements Post 1978
Unknown to many, the Honda ATC 70 had a three-year hiatus between 1975 and 1977. Although many can only speculate the reason behind the trike missing in action from the Honda lineup, this rest gave Honda time to refine the design and some components of the vehicle. Two addendums followed shortly after the youth ATV‘s comeback in 1978. Below is a summarized list of enhancements done to the ATC 70:
- 1978 models were offered in Scarlet Red versus the 1973 version that was available in Daytona Orange with a flame decal on the tank.
- Changes were made to how the carburetor idle and air-fuel mixture and brake were adjusted.
- Drive chain tension, torque specifications, and cleaning procedures were likewise changed.
- 1980 models had black number plates (VIN TB03-2000001 and up).
- Overall dimensions slightly increased, and the caster angle reduced to 20°.
- 1981 ATC 70s had a fuel tank decal change. Units were available in New Passion Red color.
- Transmission went from a 3-speed to a 4-speed constant mesh in 1982.
- Consequently, gearshift linkage, oil pump, and transmission assemblies also changed.
- 3-Kg increase in curb weight for the 1982 model attributed to the change in transmission.
- Fuel tank and reserve capacities increased from 0.66 US gallons/2.5 liters with a 0.13-US gallon reserve to 1.1 US gallons/4.3 liters with a 0.2-US gallon/0.8-liter reserve.
- Modifications to technical features and servicing procedures like cable harness and routing, rear brake lever lock mechanism, and wiring diagrams were done on 1983 and 1984 models (VIN JH3TB030*DC800006 and up).
- Aesthetic changes were also done on ’83-’84 versions. The 1984 model specifically received a non-pleated Honda ATC 70 seat cover.
- The 1985 ATC70 (VIN JH3TB030*FK000001 and up) was the only version offered in white with a blue seat cover, a “70” logo, and an automatic cam chain tensioner.
- Honda updated required special tools for servicing and maintaining the ATC 70 in its last three production years.
Distinct characteristics between the first- and second-generation ATC 70s set them apart from other model years. These earlier versions took after older Honda motorcycle models with large shell-like stamped metal frames. Their bearing assembly and exhaust system were housed inside it. Additionally, flare-like rear fenders attached to the chassis’ sides.
Honda ATC70 Specs and Features
- Engine: It is brought to life by a four-stroke, air-cooled single-cylinder OHC engine that is 80° inclined from vertical. It has a bore-stroke ratio of 47 x 41.4 mm (1.85 x 1.63 inches). The engine displacement is 72 cm3 (4.4 in3) delivered by a 17-mm Keihin PZ17 carburetor, and its compression ratio is 7.5:1. It has a forced pressure and wet-sump lubrication system.
The standalone engine weight is 41.8 lbs/18.95 Kg. Fuel tank capacity is 0.66 US gallons/2.5 liters with a 0.13-US gallon reserve. Maximum horsepower is 3.6 BHP @ 6,500 RPM (SAE), which was slightly reduced to 3.4 BHP @ 9,000 RPM (SAE 245) for 1982 and later-year versions. Maximum torque is 3.04 lb-ft (0.42 kg-m) @ 5,000 RPM.
If you want additional power, you can either go for a big-bore 88-cc carb rebuild kit or convert your ATC 70’s power mill into a Piranha 140-cc with 22-mm Mikuni carb and electronics (view on Amazon), as demonstrated in this video by Zarca Powersports:
- Drivetrain: A three-speed constant mesh transmission and chain-driven overhead camshaft deliver power to the wheels. It also has a semi-automatic centrifugal and wet multi-plate clutch. The primary reduction is 4.058, while the final is 2.500 (35/14) – changed to 36/12 when the transmission updated to 4-speed in 1982. Its gearshift is left-foot-operated.
- Ignition: It has a flywheel magneto Ignition and pull-cord, recoil starter system. Its charging system is an AC generator. It requires an NGKC7HS or NDU22FS spark plug and a 12V battery (view on Amazon) with overall dimensions of 5.31 x 3.54 x 6.57 inches (L x W x H). The recommended spark plug will differ for cold climate and extended high-speed riding – NGKC6HS or NDU20FS and NGKC8HS or NDU24FS, respectively.
- Lubrication: Oil capacity at draining is 0.8 US quarts/0.8 liters. Use Honda GN4 4-stroke oil or equivalent motor oil with a viscosity of SAE 10W-30 or 10W-40 and an API service classification of at least SJ (manufacturer recommendation of SE is now obsolete) for top performance. Depending on ambient temperature, you may use SAE 5W, 20W-40, or 20W-50 engine oils.
- Tires: The front and rear wheels are equipped with AT16 X 8-7 Honda ATC 70 tires – both with a recommended tire pressure of 2.8 psi/19.3 kPa (0.197 kgf/cm2). The vehicle wheelbase is 35.2 inches (895 mm). Carlisle Knobby ATV Tires (view on Amazon) is a good replacement in the event of tire wear.
- Brakes: There is no front brake, but rear brakes use internal expanding brake shoes and a cable-operated drum. Should you need to rebuild front brakes, check out the Complete Front Brake Rebuild Kit (view on Amazon) that includes grooved brake shoes, springs, wheel cylinders, and hardware.
- Dimensions: The overall trike dimensions are 51.1 x 31.5 x 30.9 inches (1,300 x 800 x 785 mm – L x W x H). The seat height is 22.4 inches, while the wheelbase is 35.2 inches. Dry weight is 163.1 lbs/74 Kg, whereas curb weight is 170 lbs/77 Kg (changed to 176.4 lbs/80 Kg in 1982). GVWR can go up to 230 lbs – a combination of curb weight, cargo, and accessories – plus rider weight. The minimum turning radius is 4.66 feet (55.9 inches), which makes for superb cornering.
- Exterior: The Honda ATC 70 has a backbone-type frame and plastic body material in the company’s signature red with a black seat cover. It comes with foot guards, easy-to-operate brakes, and a USDA-approved spark arrester. A speed limiter screw is on the right handlebar. A Trail Tech 752-115 Black Vapor Digital Speedometer Tachometer Gauge Kit (view on Amazon) is an excellent addition to your bike since it does not have an instrument cluster. Other must-have Honda ATC 70 parts include a Maier Rear Fender – Red (view on Amazon) for replacing dilapidated plastics and a full suspension kit.
ATC 70 Troubleshooting
Resolving this issue includes adjusting the ignition timing, valve timing, or spark plug gap if found faulty or excessive. Confirm that the spark plug gap is within the range of 0.6 – 0.7 mm/0.024 – 0.028 inches. Likewise, the inlet valve seating should also be according to spec. Using incorrect or low-quality fuel also triggers this problem, so make sure to follow manufacturer recommendations.
Several probable causes for this problem are:
- An excessively worn-out piston ring
- Head gasket
- Seized valve or piston
- A warped gasket surface of cylinder and cylinder head
- Faulty valve timing
- Inadequate compression pressure
Worn-out or seized parts are the easiest to fix as they only need replacement. Erroneous valve timing needs to be adjusted, while distorted gasketing surfaces need to be repaired.
Major causes of poor engine idling include wrong tappet clearance, insufficient (or lack of) compression pressure, and excessive valve stem clearance. Clearance-related conditions require adjusting the part to spec, while compression related ones warrant repair. Make sure to note the model year of your trike when any of these happens, as it might affect specifications. Be meticulous with 1978 and later-year models.
This specific dilemma shares most of its probable causes with the starting issue – hence the confusion when narrowing down the cause based on symptoms. The only difference is that you would also need to look into potential obstruction or damage to the valve system before going a different route. The status of the spark plug should direct you to a possible electrical problem.
It is a bit easier to identify the cause of this predicament than the rest of the Honda ATC 70 problems. White smoke indicates an issue with any of the following: oil level and pressure, quality of engine oil used, or the condition of the cylinder and piston. Black smoke points to a rich fuel mixture, which would require adjusting the carburetor. Your owner’s manual should come in handy in these situations. While you are at it, make sure to clean your carburetor thoroughly. A sonic cleaner and hot-water carb soak would tremendously help with softening any buildup and eliminating any clogs in the pathway from pilot jet to pilot screw.
Other common issues with the three-wheeler are gear shifting problems, excessive engine noise, heavy steering, and defective brakes. This set needs repair or replacement of damaged or severely worn-out parts.
- Where can I buy the 1983 Honda ATC 70 Christmas Special?
Unfortunately, you cannot purchase this specific model, nor will you find it on auction or trader sites. These units were given to local dealers to raffle off and are very rare. You may be able to find clones. However, you would know that you have spotted an original as their value is considerably higher than base models.
- How much is a Honda ATC 70 worth?
The original MSRP of a 1983 model was $549. Due to the vehicle’s rarity, current retail pricing ranges from $165 to $4,360. Units that cost $3,500 and up are usually in near-stock condition, runs perfectly, has a powder-coated frame, rebuilt power mill, and OEM plastics. You can find some of these prized collectibles (1983-1984 models) in Osaka, Tokyo, and Shizouka, Japan. The rest are scattered across different US regions.
Fun Fact: For hard-core collectors, there is a 1973 Daytona-Orange Honda ATC 70 (custom-built by Honda and gifted to the Jackson 5) waiting in Barber Motorsports Museum in Birmingham. Contact Motor Cycles (US) for more information.
- What is the Honda ATC 70 top speed? The tops speed of a Honda ATC 70 is 30 mph. Although there is no marketed figure for this three-wheeler, this video by Minnow Lake Tuning shows how fast it can go.
If you bore it out to 75-80 cm3, it can go up to 40 mph/64 kph. Adding a high-performance exhaust and bigger-sized carburetor may give you an additional 2–3 mph.
- Where is the Honda ATC 70 VIN located? You can find the VIN (which indicates the vehicle year and model) on the frame of the Little Red. Get the 13-digit code and put it in a VIN decoder to determine the details of your Honda ATC 70.
Honda Motor Company Ltd. pioneered the sport ATV industry and is the maker of the Honda ATC 70. Since its founding in 1946, the Japanese firm has come a long way in the automotive industry. Honda is a world-renowned manufacturer of top-of-the-line automobiles, power equipment, and commuter motorcycle models. It is widely recognized for its contributions in robotics, AI, and mobility and energy solutions. Despite the company’s massive success, riding enthusiasts and its avid following still look forward to Honda making a comeback with a class-leading and revolutionary sport vehicle.
Conclusion – Honda ATC 70
The reign of three-wheelers in the ATV landscape may be long gone. But it still is a treat to see a powered, vintage trike driven by an experienced rider who does not flip the vehicle over. Seeing this classic machine in action will forever be an aide-memoire of the beginnings of off-roading and how much bigger the ATV industry can still grow. Thanks to pioneers like the Honda ATC 70, 4x4s have come a long way from being just a recreational vehicle. They now add value to everyday life while continuing to fuel everyone’s desire for adventure and fun.