Yamaha XS750 Parts: Your Ultimate Guide

The Yamaha XS750, a distinctive motorcycle in the 750cc class, has carved out a unique niche for itself amongst enthusiasts. Launched in 1976, it stood out with its innovative three-cylinder configuration and shaft drive, a combination that set it apart from the predominantly four-cylinder, chain-driven offerings of its contemporaries. For owners seeking to maintain, restore, or enhance their beloved XS750, sourcing the correct parts is paramount. This guide will not only point you towards reliable suppliers but also explore the significant evolution of the XS750 engine, particularly around the 1978 model year, and the emergence of the stylish 'Special' variants.

For those on the hunt for Yamaha XS750 motorcycle parts, Mikes XS stands out as a premier destination. They boast a substantial inventory specifically catering to vintage Yamaha motorcycles, including the XS750. With the added advantage of same-day shipping within the continental US, Mikes XS is well-equipped to meet a wide range of your XS750's needs, ensuring your classic machine stays on the road.

The Evolution of the Yamaha XS750 Engine: A Closer Look

Yamaha's approach to the 750cc market was refreshingly novel. Instead of following the crowd with another four-cylinder sportbike, they introduced the DOHC Triple in 1976. This innovative engine configuration, paired with shaft drive, was a bold statement. While the basic architecture remained consistent through to the 1979 model year, Yamaha continuously refined the powerplant, addressing rider feedback and evolving emissions standards.

Let's examine the key changes and improvements, particularly focusing on the transition to the 1978 XS750E model:

From XS750D to XS750E: Engine Enhancements

The initial 747cc engine, featured in the XS750D, underwent several significant updates. The exhaust system was a notable point of modification. Initially a 3-into-1 system, it was changed to a 3-into-2 setup on the 750 2D model. This change, along with other engine revisions, helped to shift the engine's vibration band to a less intrusive speed range, simultaneously improving performance.

The 1978 XS750E model marked a substantial leap forward in engine development:

• Compression Ratio Increase: The compression ratio was bumped from 8.5:1 to a more potent 9.5:1. This generally leads to increased power and efficiency.
• Cam Timing Modifications: Changes to the cam timing further optimised the engine's breathing and power delivery across the rev range.
• Electronic Ignition: The introduction of electronic ignition provided a more reliable and precise spark, contributing to smoother running and easier starting.
• Carburetion Refinement: More precise carburetion ensured a better fuel-air mixture, leading to improved performance and cleaner emissions.

The results of these changes were substantial. The XS750E boasted considerably more power, a higher redline (9000 rpm compared to the D model's 7500 rpm), and a cleaner exhaust output to meet stringent emission regulations.

1979 Model Year Refinements: Balancing Power and Emissions

For the 1979 model year, Yamaha continued its refinement process, primarily driven by further emission requirements. The compression ratio was slightly reduced to 9.2:1. Importantly, Yamaha continued to recommend regular unleaded fuel, and the test bikes performed admirably on both regular and unleaded varieties.

A key focus for 1979 was vibration control. The engine mounts were modified to minimise felt vibration at typical highway cruising speeds. This was an ongoing effort, as the original XS750D was noted for an irritating vibration at certain speeds. The 2D model shifted this vibration band, and the more powerful E model saw a slight increase in vibration. By the 1979 'F' model, vibration control was more effectively managed.

Performance Characteristics: The Charm of the Triple

The heart of the XS750's appeal lies in its unique engine character. The 120° crankshaft produces a distinctive, rocking beat at lower engine speeds, a sound that emanates crisply from the twin short mufflers. As the revs climb, these beats smooth out into a gentle hum at highway speeds. This provides a pleasing auditory experience for the touring motorcyclist.

In terms of power delivery, the XS750 excels at lower RPMs, often outperforming other 750cc bikes in this regard. This makes for effortless riding in urban environments, allowing riders to accelerate from a standstill with minimal clutch input. The Yamaha feels comfortable at higher gears than its Japanese competitors, contributing to a more relaxed touring experience.

While the engine revisions brought more power at higher RPMs, they did so with minimal sacrifice of low-end torque. However, in outright acceleration tests like the quarter mile, the XS750, in its contemporary form, was a half-second slower than the quickest Japanese 750s. Nevertheless, its superior roll-on acceleration in real-world riding situations often made it feel faster.

Gearing and Drivetrain Considerations

The output shaft gear ratio was revised on the E and later models, changing from 3.262:1 to 3.582:1. This increased engine speed at 60 mph by approximately 400 rpm. While this might sound counterintuitive for relaxed touring, the revised gearing proved remarkably effective. At 60 mph, the Yamaha was turning around 4522 rpm, and at typical freeway speeds, it was comfortably humming around 5000 rpm. This higher cruising speed effectively placed the engine above its noted vibration periods, contributing to a smoother ride.

Despite the overall improvements, the gearbox action could be less refined. A noticeable crunch could occur when shifting into first gear when cold, even with a properly adjusted clutch. Upshifts could also be noisy, and the shift lever sometimes hesitated in the up position, potentially hindering the shift into third gear. Driveline slop was also present, leading to jerky changes, particularly at lower speeds. The CV carbs, while contributing to smooth throttle response, could sometimes react too quickly to throttle inputs, especially when closing the throttle.

Suspension: A Work in Progress

Suspension development on the XS750 also saw continuous refinement. The original model offered a moderately plush ride. The 2D model softened this further with longer travel front forks and softer rear spring and damping rates. For 1978, Yamaha stiffened the rear springs and increased shock damping considerably. A three-position front fork spring preload adjuster was also added.

The rear suspension remained consistent for the 1979 models. However, the 'Special' variant introduced new leading-axle front forks, still featuring the three-position preload adjusters. Despite these changes, the suspension, particularly on the Special, was noted to be somewhat stiff, with excessive compression damping in the rear shocks. Even with maximum preload, the rear could bottom out on rough roads with a passenger. The front forks performed better, absorbing shocks adequately. Overall, the suspension was considered an area where further improvements would be beneficial.

The Yamaha XS750 Special: Style Meets Substance

Yamaha recognised the appeal of customisation and introduced the 750 Special. This variant took the standard touring platform and applied a distinct 'chopperised' aesthetic. Key visual changes included:

• Cowboy-style handlebars
• A rounded, peanut-shaped fuel tank
• Increased front-end rake
• Leading-axle forks
• Short, stylish mufflers
• A stepped seat
• Restyled instruments
• A cleaner rear fender

While Yamaha wasn't the first to offer a factory-customised motorcycle, the Special's styling resonated strongly with the market. Surveys indicated a significant portion of motorcyclists favoured the 'normal' motorcycles, but a large segment also appreciated the style of the Specials. The 750 Special proved to be a highly successful transition, with nearly half of all 750 Yamahas sold being the Special variant.

Beyond the aesthetics, the Special offered some practical advantages. The fuel tank, contrary to initial specifications, held a more generous 5.1 gallons compared to the standard model's 4.5 gallons, and featured two petcocks for a larger usable reserve. The mufflers were particularly well-designed, being compact enough not to impede saddlebag mounting and positioned ahead of the axle for easier tyre changes.

Brakes and Other Notable Features

Both standard and Special Yamaha Triples came equipped with a suite of modern features for their time, including turn signal cancellers, mag-style wheels, and triple disc brakes. The triple disc brakes were powerful, offering excellent modulation and stopping power in dry conditions. However, their performance was notably compromised when wet.

Other appreciated features included a 55/60 watt halogen headlamp, providing a bright and well-defined beam. For those who appreciated a touch of old-school reliability, the XS750 also featured a kick starter, and the ability to start the engine without pulling in the clutch was a convenient touch.

Handling and Comfort: A Touring Focus

The XS750 was primarily conceived as a touring motorcycle, and its handling characteristics reflected this. At speed, the bike was steady and tracked straight, though cornering required a more deliberate effort compared to some of its rivals. While acceptable for general use, it didn't match the sharper handling of other 750cc Japanese offerings.

The seating position was generally found to be comfortable for long days. The handlebars, in particular, worked well with a windshield or fairing, allowing a relaxed rider posture. Without a fairing, however, the handlebars could become less comfortable and less conducive to spirited riding. The low-speed manoeuvrability of the Special was noted as being slightly clumsy, partly due to its unique seating position, making low-speed adjustments a bit awkward.

Comfort was enhanced by rubber-mounted handlebars and footpegs, which effectively muffled engine vibration during extended rides. While this did introduce a slight degree of insecurity to the bike's handling, the comfort benefit for long-distance touring was undeniable.

Carrying Capacity and Load Considerations

For most touring duties, the XS750 proved to be a capable mount. However, for carrying heavy loads, it could be overwhelmed. With a Gross Vehicle Weight Rating (GVWR) of 960 lb and a load capacity of 414 lb (with a half tank of fuel), the weight ratings were reasonable. The limitation, however, arose when weight was concentrated at the rear, potentially overloading the rear tyre.

Unlike many motorcycles with conventional swingarms, the XS750's swingarm, housing the driveshaft, limited rear tyre clearance. A 4.00 x 18 tyre was the maximum size that could be fitted. This limitation was partly a consequence of the desire to maintain the 'chopper' image, which often involves wider rear tyres.

Frequently Asked Questions

Q1: Where can I find Yamaha XS750 parts?

A: Mikes XS is a highly recommended source for Yamaha XS750 motorcycle parts, offering a wide selection and efficient shipping.

Q2: What were the main engine changes in the 1978 XS750E?

A: The 1978 XS750E featured an increased compression ratio (9.5:1), revised cam timing, electronic ignition, and more precise carburetion, leading to increased power and a higher redline.

Q3: How did the XS750's vibration improve over the years?

A: Yamaha made several adjustments, including exhaust system changes and modified engine mounts, to shift the engine's vibration band away from common highway speeds, improving rider comfort.

Q4: What distinguishes the XS750 Special from the standard model?

A: The Special featured distinctive styling elements like cowboy handlebars, a peanut tank, leading-axle forks, short mufflers, and a stepped seat, along with a larger fuel tank capacity.

Q5: How was the XS750's handling compared to other 750cc bikes?

A: The XS750 was considered steady at speed but required more effort to turn than some competitors. Its handling was deemed acceptable for ordinary use but not as sharp as other Japanese 750s.

In conclusion, the Yamaha XS750, in both its standard and Special guises, offered a unique blend of innovation, style, and touring capability. While not the fastest, smoothest, or best-handling 750 on the market, its distinctive triple-cylinder engine, shaft drive, and thoughtful features made it a compelling choice for motorcyclists seeking something a little different. With reliable parts suppliers like Mikes XS, keeping these classic machines on the road is an achievable and rewarding endeavour.