A true off-roading enthusiast would undoubtedly recognize the Honda 350X ATC as the archetype of modern-day utility vehicles but with three wheels instead of four. This head-turner is not only a serious trail machine but also included in the illustrious Big Red bikes – a part of Honda’s sport ATC lineup that began in the ‘70s. Given its racing lineage and prestige, it would be fascinating to know what this reputable vehicle has to offer.
Produced from 1985 to 1986, the Honda 350X ATC (Big Red 350) featured crisp brakes, grippy tires, and a powerful 350-cc mid-range motor. It was the penultimate installment to the legendary Big Red series – a lineup of performance-built trikes designed for aggressive trails and racetracks.
The Honda 350X was only in the off-roading limelight for two years. But no period is too short for something as great as this bike. Despite its inability to execute fancy stunts and jumps and its need for body English to unleash its potential, the 350X was a standout, nonetheless.
Savvy aficionados would undoubtedly agree. But if you are not quite convinced, this guide will enlighten you on the huge influence this three-wheeler had on present-day utility vehicles.
The Honda Big Red 350
The Honda 350X ATC is 9th in the line of all-terrain cycles and the 3rd generation of Big Reds released by Japanese manufacturer Honda. Introduced in 1985, the Honda 350X launched during the height of the ATC craze, alongside other revolutionary machines – and had a lot of promise. Honda engineers had racing in mind during the design process of the trike.
However, it turned out to be more of a sport machine than a racer. Due to the 1988 Consent Decree (or ATC ban), it only lasted in the market for two years before its demise. Consequently, Honda did not have the opportunity to further develop the machine, as the industry shifted its direction towards four-wheelers.
Often compared to the ATC250R, this Honda ATC received little to no improvements during its short-lived production run. The only notable changes to the wheeler are the increase in carb size (from 31 to 32 mm) and the oil pump upgrade. Everything else about the machine remained untouched.
Interestingly, it was also the only Honda ATC that was not equipped with the Pro-Link rear suspension found on its siblings – a requisite back in the day for Honda racing bikes. Instead, its suspension system featured a leading-axle fork as opposed to a trailing-axle design.
Nonetheless, the Honda 350X had some impressive features – including nearly doubling the displacement of earlier generations of the Big Red series. On the outside, it looked like a three-wheeled UTV stripped off of its cargo racks. It featured components somewhere in the middle of Honda’s top-end and entry-level trikes back in the day, making it a perfect go-to vehicle for recreational riders.
All in all, it is a much-coveted trailer and racing machine, given proper upkeep, performance mods, and a skilled rider.
1985 – 1986 Honda 350X Specs & Features
Engine
An air-cooled, forward-inclined 4-stroke OHC power mill with an 81 × 68 mm (3.19 × 2.68 inches) bore-stroke ratio, an 8.5:1 compression ratio, and 4-valve-per-cylinder design powers the vehicle. Engine displacement is 350.4 cm3 (21.38 in3) delivered by a 31-mm dual-valve Keihin carburetor.
The ATC’s engine configuration lends to its 60 – 65 mph (97 – 105 km/h) top speed, horsepower of 26.6 hp/27 PS @ 7,000 RPM, and maximum torque of 29.4 Nm (3.0 kg-m, 21.7 ft-lb) @ 6,000 RPM.
Gearing adjustment and porting/polishing are proven to render a top-end rating of up to 72 mph (116 km/h) on flats and going downhill. But even after these tweaks, the ATC250R is still faster at 74 mph (119 km/h).
Fuel & Lubrication
It has a forced pressure (wet sump) lubrication system with an oiled polyurethane foam air filter like a UNI Stage 2 Air Filter NU-4134ST (view on Amazon). Fuel tank capacity is 10 L/2.65 US gallons with a 2 L/0.53 US gallon reserve. For top performance, use SAE 10W-40 Honda 4-stroke oil (without graphite or molybdenum additives) or its equivalent. Depending on ambient temperature, you may also go for SAE 5W, 10W-30, 20W-40, or 20W-50 viscosity grades.
Service manual recommendation is an SE/SF API-certified motor oil (now obsolete) – API-grade SJ+ oils meeting JASO T903 MA standards would be a great alternative.
(Trivia: For the 1986 Honda 350X, the oil pump was redesigned to address issues with the engine being starved of oil when performing wheelies or being left in an upright or close-to-vertical position.)
Drivetrain
A six-speed constant mesh return system and a wet, multi-plate clutch assembly deliver power to the ground. A 520 O-ring chain (with 90 links) handles wheel spin, and a rack-and-pinion steering system makes for convenient vehicle control and maneuverability. The manual tranny has a five-up-one-down gearshift pattern (1-N-2-3-4-5-6, left foot operation). This powertrain combo makes the Honda 350X worthy of its sport lineage. For riders looking to restore the bike to OEM specs, the stock gear ratios are below:
| Primary Reduction Ratio | 2.833 (68/24) |
| Final Drive Ratio | 3.077 (40/13) |
| Transmission Gear Ratio (1st) | 2.750 (44/16) |
| Transmission Gear Ratio (2nd) | 2.050 (41/20) |
| Transmission Gear Ratio (3rd) | 1.609 (37/23) |
| Transmission Gear Ratio (4th) | 1.308 (34/26) |
| Transmission Gear Ratio (5th) | 1.103 (32/29) |
| Transmission Gear Ratio (6th) | 0.935 (29/31) |
Ignition & Lighting
It has a fully transistorized CDI (Capacitor Discharge Ignition) and a primary kick-start system. A 13.5 – 14.5V alternator with a rated output of 200 watts @ 5,000 RPM serves as the trike’s charging system, while an A.C. generator powers up the lamps and other electronic accessories (if any).
Ignition timing is 10° BTDC @ 1,400 RPM ± 100 (initial “F” mark) and 30° BTDC @ 3,500 RPM ± 200 (full advance). Additionally, the bike requires an NGK DR8ES-L or Nippon Denso X24ESR-U spark plug with a 0.6 – 0.7 mm gap.
Unlike current ATVs, this particular Big Red does not come with a battery. Should you need to equip it with one, you first need to wire a regulator/rectifier to it to have DC voltage, permitting the addition of a battery. Ensure to leave the ignition source coil out and not connect the CDI circuit to the regulator/rectifier, as the latter gets its dedicated power feed from the stock alternator.
While you are at it, replace stock lamps with 12V lighting compatible with the regulator/rectifier. Opt for a YTX12-BS battery (view on Amazon) format after successfully upgrading the ATC’s electrical components.
Tires & Brakes
Stock rubber consists of low-pressure, tubeless 23.5 x 8-11 Ohtsu tires at the front and 22 x 10-9 Ohtsu tires at the rear, leading to the Honda 350X’ comfortability and responsive steering. They mount on rims that are either ITP steel (91R411) or ITP aluminum (T914110) with a 4/110 bolt pattern. Hydraulically operated front and rear single disc brakes complete the Honda ATC’s tire-and-wheel assembly and lend to its excellent stopping power.
Recommended tire pressure for the front is 27.6 kPa (0.28 kgf/cm2, 4 psi) and 20.6 kPa (0.20 kgf/cm2, 3 psi) for the rear. Maxxis MU02 Zilla Bias Tires (view on Amazon) are among the top tire replacement choices by off-roaders and enthusiasts as they work well with the Honda 350X ATC.
Suspension
The Honda 350X suspension system features a 203-mm telescopic fork at the front and a 194-mm swingarm with remote-reservoir Showa gas shocks (rebound and compression damping adjustable) – providing wheel travel of 8.0 inches and 7.6 inches, respectively. Trail length is 34.5 mm with a caster angle of 23°. The assembly is only slightly behind the suspension specs of the iconic Honda ATC250R and mounts on a semi-double-cradle steel frame.
Enthusiasts had hoped the 350X benefited from Honda’s Pro-Link linkage system and that the manufacturer upgraded the vehicle’s miserly ground clearance of 4.7 inches (120 mm) to match its long-travel suspension. The 4-inch ride height isn’t necessarily a setback for most riders. But those who frequent rock-laden trails and bumpy terrain do find it unfavorable.
Dimensions
Overall vehicle dimensions of the 1985 Honda 350X are 74.4 x 43.9 x 42.6 inches (1,890 x 1,115 x 1,082 mm – L x W x H). The length and width were retained the following year, but the Honda ATC’s height was reduced by less than an inch (42.3 inches, 1,075 mm).
Seating is just two inches shy of the ideal height for big, tall riders at 29.5 inches (750 millimeters). The 11.4-inch (290 mm) footpeg height secures the rider in place on the three-wheeler, instilling confidence.
Versus its counterparts weighing 490 lbs (222.3 Kg) on average, the three-wheeler is considered a lightweight in its class at 320 lbs (145 Kg).
Exterior
The Honda ATC 350X frame comprises mild steel tubing that is ¾ inch thick (versus the ATC250R’s tubing, which measures 1 1/8 inches). Because of this, the chassis is unsuitable for MX tracks in stock form and would need to be beefed up for racing applications. Like the rest of the ATCs in the Big Red lineup, its plastic body panels were made available in white, blue, or red with a blue or red seat cover.
Other standard inclusions are front and rear fenders, handlebar, hand grips, dual 35-watt headlights, a 5-watt taillight, and a snorkel-like intake.
Cost of a Honda 350X
At the time of its launch, the suggested list price for the 1985 Honda 350X ATC was $2,248, while the 1986 Honda 350X was $2,498. In base form, a secondhand unit would generally cost from $360 to $2,795. Since the series only had two models and no trims, fluctuations in current retail pricing would depend on any performance upgrades or any other features added.
Restoring a 350X to showroom condition would cost at least $2,700 to $3,200 (on top of its resale value). Those below $500 usually sell for parts. Conversely, trikes worth $2,000 or higher are rare finds – generally in good working condition and minimal cosmetic damage.
Bringing Back the King
With off-roading classics like the Honda 350X, there are only two routes for enthusiasts – a project build that transforms the aged bike into showroom condition or a full restomod that takes both riders and onlookers down memory lane.
Although far from inexpensive, either is an undertaking that is difficult to rebuff, as it would mean seeing an all-new 350X in the flesh. If you are willing to take on the challenge, here are a few things entailed in the project:
Gusseting & Powder Coating
The Honda 350X’s mild steel tubing is the primary reason most riders deem it unsuitable for the track. Hence, it is an excellent idea to strengthen the frame with gusset kits, even if you only use it for trail riding.
Remember to replace all stock bearings with new ones to prevent the chassis from wobbling unnecessarily. Finally, give the machine a good powder coating once the frame is repaired and fully reinforced for a clean, polished look.
Suspension Upgrade
Similar to other Honda ATCs, valve emulators best enhance the 350X stock suspension. Because valve emulators perfectly mimic the function of a cartridge fork, they allow independent tuning of compression and rebound circuits (with the help of stiffer fork springs). Getting high-flow valve pistons further improves the machine’s handling characteristics and bottoming resistance.
Swapping out the stock rear suspension for a Chromoly swingarm is also strongly recommended but not necessarily required.
Increase in Power
While the power output of the 350X is not considered conservative, many owners find the stock head pipe to be limiting. That said, most of them go for high-performance aftermarket Honda 350X parts to replace OEM ones not up to snuff.
Conversely, others choose professionally modified exhaust systems to open up the vehicle’s intake and broaden its powerband – in addition to having custom valving and cylinder porting done.
Well-known racing outfitters like CT Racing specializes in project builds and can help out with your needs – barring budget restrictions.
Pimped Up Styling
Aftermarket polypropylene plastics are in abundance nowadays – and consumers could not be happier. These plastics make bodywork repairs easier, ultimately breathing new life to vintage wheelers. They also improve the aggressiveness of the ATC, especially when paired with racy handguards, body-matching tank shrouds, DG Performance Nerf Bars (view on Amazon), Chromoly footpegs, Pro Taper 7/8 handlebars (view on Amazon), and decals.
Sometimes, changes to the stock tire-and-wheel assembly (for instance, trading the original brakes for steel-braided brake lines or going for billet-center bead lock wheels) are done for cosmetic purposes more than function. Today, numerous options exist, providing a wide array of fitment and line color options and allowing 350X owners to personalize their wheelers.
About Honda
All great things begin with a great concept – and the story of Honda Motor Company Ltd. is no different. Founded in 1946, former mechanic Soichiro Honda began producing surplus engines and motorized bicycles and grew his company to the automotive market leader that it is today. Honda maintains its strong presence in the motorcycle and ATV industries and even in Formula 1 racing circuits.
Furthermore, its armada of product offerings reflects the company’s passion, strife for excellence, and commitment to improving people’s lives through mobility advancements.
Conclusion – Honda 350X ATC Review
Despite earning the “death mobile” moniker, the Honda 350X is safe to ride, provided you know what you are doing. Its suspension system can be a drawback, but that does not make power slides less fun on this three-wheeler. If anything, it makes the 350X a more challenging and equally rewarding build project.
Flaws aside, this machine has proven itself second to none – even when pitted against current 350-cc quads. Ultimately, choosing to ride this revered three-wheeler entails doing so with a grain of salt – it is, after all, an off-roading legend.
Kris is an avid off-roader and outdoor enthusiast who loves to brave the elements and take on challenging terrain. He also enjoys sharing his passion and knowledge with others so that they, too, can appreciate the ride.
About Kris