Honda CX500: The Innovative V-Twin That Vanished

The Rise and Fall of Honda's Unconventional Icon: The CX500

It was the spring of 1978, and the motorcycle press, gathered for a Honda function in Los Angeles, expected another predictable off-road machine. After a decade of testing, the author, Derek Pickard, was ready for a change. Honda, then trailing Yamaha in the off-road arena, had summoned the press with little fanfare. What unfolded, however, was a revelation that left everyone utterly stunned. Mere months after wowing the world with their 1000cc six-cylinder, Honda unveiled something entirely revolutionary: the CX500. This wasn't just another bike; it was a bold statement, a departure from convention that borrowed nothing from anyone, least of all from its own existing range. Here stood a robust 500cc V-twin, complete with shaft drive and pushrods, a design that seemed to defy the established norms. In a market beginning to hint at a resurgence for mid-weight tourers, with Moto Guzzi having recently announced their own lightweight V-twin, the CX500's arrival was seismic. Honda's formidable marketing power and vast dealer network seemed to guarantee its success. Early test rides confirmed its appeal. Despite being on the heavier side for a 500cc machine, it offered a respectable 50bhp and a willingness to rev, with virtually zero torque reaction. It excelled at the core duties of a tourer, and critical reception from testers worldwide was overwhelmingly positive. The public, it seemed, was ready to embrace this innovation.

And embrace it they did. The CX500 rapidly became a bestseller. Its distinctive looks, coupled with a sweet-natured riding experience confirmed during demo rides, captivated buyers. Dealerships reported booming sales, and Honda's gamble paid off handsomely. The CX500 found favour across continents: Americans navigated city streets and highways, Germans cruised their autobahns, and in Britain, it became the workhorse of choice for London's demanding despatch riders. Honda's commitment to Research & Development had yielded a motorcycle packed with innovative features: the V-twin engine with pushrods and a high-revving nature, liquid cooling, a side-shift gear lever, shaft drive, and the clever integration of the engine as a lower frame member. However, even the Japanese giant wasn't infallible. A recall was swiftly issued to address a faulty cam chain tensioner arrangement, a fix that dealers expedited, marking the affected engines with three small dots next to the engine number. Remarkably, this was the only significant widespread issue reported. Riders simply enjoyed revving their CX500s for years on end.

Evolution and Experimentation: The CX500 Range

Following its initial success, Honda introduced several upgrades and variations. A US-style cruiser model emerged, featuring taller handlebars, a smaller fuel tank, and a reduced rear wheel size, giving it a distinctly American aesthetic. Performance enhancements included the addition of dual front discs, although the smaller 240mm diameter discs offered only a marginal improvement over the original single 270mm disc. A small screen was also added to some models, along with a rerouting of crankcase venting to the airbox. The CX500's production line in Japan ran at full capacity, struggling to meet the insatiable global demand. The mid-1980s saw Honda further refine its popular model. In 1982, the 'Sport' version was released, widely considered the pinnacle of the CX500 line. This iteration boasted thicker fork tubes (33mm to 37mm), twin-piston callipers, and an automatically adjusting cam chain tensioner, a significant improvement over the earlier manual system. The most audacious experiment, however, was the CX500 Turbo. A complete re-engineering of the CX500, complete with a distinctive fairing and 'Turbo' badging, it was a serious performance machine. Unfortunately, its prohibitive price and inherent complexity led to its quiet discontinuation after only a year.

The Bigger CX and the Sudden End

The anticipation for a larger displacement CX model was palpable. In 1983, Honda answered the call with the CX650. Enlarged to 650cc, this new model, however, retained the short-stroke design and consequently gained weight and length. While it featured the then-fashionable monoshock rear suspension, it failed to capture the market's imagination. Sales plummeted dramatically. Honda quietly ceased CX500 production, replacing it with the rather unusual VT500, which oriented the engine longitudinally within the frame. This new engine, with a slightly longer stroke, offered improved flexibility. However, the market's rejection of both the CX650 and the VT500 was swift and decisive. Both models were soon dropped, marking the end of the CX lineage. The innovative transverse V-twin with its characteristic shaft drive, a design that had once captivated riders, was relegated to history. The much-discussed 750cc long-stroke variant never materialised, and Honda seemingly abandoned the entire CX concept, leaving Moto Guzzi to continue with its own V-twin shaft drive designs.

Why Did Such an Innovative Bike Disappear?

The abrupt end of the CX500 can be attributed to a confluence of factors, primarily rooted in Honda's corporate culture and strategic direction. Japanese manufacturers are known for their relentless pursuit of innovation and rapid product cycles, constantly pushing R&D budgets to fund future models. The CX500, despite its enduring popularity, became a casualty of this philosophy. By Japanese automotive standards, the V-twin platform had been around for a considerable time. While it had cultivated a dedicated following, Honda, with its vast resources, was ready to move on. The company was heavily invested in promoting its new V4 engine technology, which was being rolled out across various capacities from 400cc to 1000cc. The V4 was the future, and nothing, not even rider preference, tradition, or niche market success, was allowed to impede its progress. The CX500, a brilliant but ultimately independent design, simply didn't fit into this new strategic vision.

Uniquely Brilliant: The CX500's Engineering Prowess

The CX500's most significant advantage over its contemporaries was its sheer uniqueness. While some drew comparisons to Moto Guzzi, the CX500 was fundamentally different. It featured a much shorter stroke, four-valve cylinder heads that rotated, an 80-degree V-angle, liquid cooling, and the legendary long-term durability synonymous with Honda. The engine itself was a visual spectacle, prominently displayed within the frame, polished and lacquered to a mirror finish. Its aesthetic appeal was undeniable, and riders universally admired its looks. Beyond its visual charm, the CX500 incorporated sophisticated engineering solutions. Honda's extensive R&D had redefined the V-twin layout. By counter-rotating the transmission relative to the front-mounted clutch and then feeding power back to the gearbox, Honda effectively minimised in-line torque reaction, achieving a level of refinement rarely seen. The integration of the barrels into the crankcase, a feature borrowed from automotive design, further enhanced its solidity. The cylinder heads were rotated by 22 degrees, allowing the carburettors to be positioned closely together, creating a compact layout that avoided rider knee interference. This clever arrangement also resulted in a unique piston design where the valve cutaways were not aligned with the gudgeon pin. While seemingly a minor detail, this prevented the adaptation of pistons for big-bore conversions, a limitation that would prove significant for future development.

Performance Characteristics: A Rev-Happy Tourer

The CX500, while heavy for a 500cc machine, was well-suited to its 50bhp touring output. Achieving its best performance required a rider to embrace the gearbox, reaching for the higher revs. This was not a bike for relaxed, low-rpm cruising; it demanded to be ridden with vigour. At 100 kph, the tachometer registered over 5000 rpm, and with a fixed 3.09:1 drive ratio, there was no option for taller gearing. The engine's short stroke gave it the bore characteristics of a 250cc twin, underscoring its design intent: to rev freely and reliably for extended periods. Unlike other tourers of its era, the CX500 could be pushed to its limits without complaint. Below 3000 rpm, the engine was relatively docile, but once it passed the 4500 rpm mark, the 36mm CV carburettors, camshaft timing, four-valve heads, and short stroke all worked in harmony, propelling the bike towards its 9700 rpm redline. A key advantage appreciated by owners was the advanced cylinder head design. Equipped with top valve seats to accommodate unleaded fuel and generous squish in the combustion chambers, it achieved a 10:1 compression ratio, allowing it to run happily on readily available, lower-octane fuel. The Turbo variant, while offering blistering acceleration reminiscent of a jet, suffered from the typical turbo lag and peaky power delivery, making it a complex and often frustrating machine for many.

Common Issues and Maintenance Considerations

Considering its unique design, the CX500 proved to be remarkably reliable. Apart from the initial cam chain tensioner issue, most models performed admirably with minimal servicing. Early fixes were identifiable by three dots next to the engine number. The magneto-type CDI system allowed for push-starts even with a flat battery, and the twin CV carburettors provided consistent performance in both hot and cold conditions. Early models featured thin front discs, requiring frequent replacement under hard riding. Later twin-spot callipers were prone to contamination, leading to sticking brakes due to exposed pistons. The 1982 model's automatic cam chain tensioner, while convenient, was often overlooked, potentially leading to wear and eventual failure if not periodically checked. High-mileage machines may require the 'CX Triple Bypass,' which involves replacing the cam chain tensioner, water pump seal, and stator (new units are scarce). Internal corrosion can also be an issue if the cooling system is topped up with plain water, though the copper and brass radiators are generally repairable.

The problems encountered with the CX500 pale in comparison to those found on the CX650. The 650cc models suffered from rapid wear in the top end, and replacement parts, particularly the unique 7mm valve adjusters and camshafts, are now virtually non-existent. Owners of 650s are often forced into expensive modifications, adapting CX500 components to keep their bikes on the road. The rare VT500 models were also plagued by clutch issues, a notable misstep by Honda.

Racing Pedigree and Modern Relevance

While Honda considered racing the CX500 in production events, early tests revealed limitations. A stock bike provided to a professional racer highlighted insufficient ground clearance and basic circuit performance, deeming it unsuitable for serious competition. The CX500 was, first and foremost, a tourer. Even in New Zealand, few CX500s found their way onto the racetrack. Despite these historical limitations, a few CX500s do compete in 'Forgotten Era' historic racing classes, proving surprisingly competitive with modifications such as increased capacity, shaved heads, and wilder camshafts. For contemporary owners, some modifications are considered vital. A fork brace can mitigate flex in the early 33mm forks, or an upgrade to the later, thicker forks (standard on 650s) is recommended. Improved rear suspension units, such as Konis, were a popular upgrade. Good quality tyres are essential for the original, thin wheels. Mechanically, the engine is already a strong performer, and modifications beyond less restrictive mufflers are generally not advised. The original Comstar wheels, while visually distinctive, are brittle and non-user-friendly; bent units must be discarded.

Parts Availability and Enthusiast Communities

The primary challenge for CX enthusiasts today lies in sourcing parts for the 650cc models, with even online marketplaces offering limited options. However, the CX500 remains a viable proposition for both daily riding and classic motorcycle use, with most parts still readily available. Recent difficulties have been noted with new indicator lenses and master cylinders. The Australian CX user group on the internet is a vibrant hub for enthusiasts, with many international members participating. The group's linchpin is 'Doctor Don' Seedsman, a Melbourne-based CX500 aficionado and part-time mechanic. With over a decade of dedicated service to the CX community, Don possesses an unparalleled understanding of these bikes and a substantial stock of parts, often knowing what can be adapted. His personal collection includes a Cruiser, Sport, and Turbo model, a testament to his passion. His dedication highlights the enduring appeal and the strong community support surrounding the Honda CX500, a truly unique machine that left an indelible mark on motorcycle history.

Frequently Asked Questions

Does a Honda CX500 engine oxidize?

Yes, the Honda CX500 engine is all aluminium and, if operated with only fresh water in the cooling system, it will oxidize. It is crucial to use a 50/50 mixture of ethylene glycol antifreeze and water to prevent oxidation and corrosion.

What was the main issue with early CX500 models?

The primary issue with the very first CX500 models was a faulty cam chain tensioner arrangement. This was addressed through a recall, with affected bikes marked by three dots next to the engine number.

Why did Honda stop producing the CX500?

Honda discontinued the CX500 as part of a strategic shift towards its new V4 engine technology. Despite the CX500's popularity, it was deemed a platform that had run its course, and resources were redirected to the V4 program.

Are CX500 parts still available?

For the CX500, most parts are still available, making it a realistic option for daily riding and classic use. However, parts for the later CX650 models are significantly harder to find.

What were the key innovations of the CX500?

Key innovations included its transverse V-twin engine with pushrods, liquid cooling, shaft drive, the engine's integration as a lower frame member, and sophisticated engineering such as counter-rotating transmission to minimise torque reaction.

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