By the time the RD400 was launched in 1976, Yamaha had nearly fine-tuned its platform. At the very core of the bike lay a potent 399cc, 44hp two-stroke twin engine. The car boasted a pioneering implementation of disc brakes at both the front and rear, coupled with carefully calibrated geometry that enabled swift handling. It also exhibited impressive acceleration, capable of completing a standing quarter-mile in a creditable 14.1 seconds. As the throttle was twisted, the engine surged to life with a sudden, almost startling ferocity that might easily leave an uninitiated bystander breathless; when fully unleashed, it could potentially blast past 100 miles per hour.
Due to the United States’ implementation of stricter emission regulations and the rapid proliferation of four-cylinder motorcycles, the RD series lost its market appeal in the early 1980s. For those who had experienced the thrills of riding a two-stroke RD in its prime, the nostalgia remained stubbornly hard to ignore.
Coti Sanders of Southern Maine has been passionate about sailing since his childhood days. As a young rider, he honed his skills on two-stroke dirt bikes and Yamaha Banshees, cultivating a distinct approach to extracting every last bit of performance from these lightweight machines while being intimately familiar with the nuances required to get the most out of an RD Yamaha. He recalls the moment he finally acquired his first bike, knowing that its humble beginnings would propel him onto a path of adventure. Around twelve years ago, I stumbled upon this bike as a means of transportation and swapped out my ATV for it.
As Coti had no pressing deadline, he devoted himself to meticulously restoring the ’76 Yamaha RD400, driven solely by the goal of making it roadworthy. Despite initial momentum, life’s unpredictability intervened, causing the project to stall indefinitely. Two years prior, Coti had deemed it sufficient, deciding that his RD400 motorcycle had earned the attention it warranted.
With resolute determination, Coti set out to revamp the entry point of his bike, deliberately reapproaching each step to ensure he remained focused throughout the entire process. The process initiated by addressing key enhancements.
A set of golden upside-down Suzuki GSX-R forks has been retrofitted into the RD400 body. The new brakes feature a high-performance twin-disc setup, inspired by the renowned Yamaha R1, replacing the iconic RD’s sole 46-year-old braking system. Coti machined and drilled the rotors to give the newly installed brake setup an added layer of visual appeal. The spoked wheel grasps onto a Suzuki GT750, with a modified Yamaha TZ250 fender situated above it.
Coti had a soft spot for the distinctive Yamaha RD400 gas tank, which is why he went to great lengths to preserve the rare unit. To achieve a seamless appearance, he has cleverly recessed the filler to create a flush finish.
Subsequently, Coti completed the engine’s work entirely on his own. The project entailed a comprehensive engine overhaul, featuring upgraded Banshee cast pistons of increased size. To preclude piston skirt contact with the crankshaft, Coti opted for precise shaving, while clever cylinder porting allowed him to harness the benefits of his fresh upgrades. To boost performance, larger reed cages sourced from a Yamaha YZ off-road bike were incorporated, while Coti designed an exhaust system utilizing their proprietary formula.
“When I designed the bike, I specified that the enlargement chambers should be located on the opposite side of the exit,” he remarks. With a hint of humility and self-deprecation, “I fabricated the exhausts myself because I’m a frugal individual” showcases Coti’s DIY skills and creativity, as evident in his impressive two-stroke exhaust craftsmanship, leaving little doubt about his talent. Beneath the engine lies a custom-fabricated metal stomach pan, crafted by him personally as an additional feature.
Critical mid-build issues arose when Coti was unexpectedly invited to showcase his RD400 at a prominent event. As he shares the memory, a smile creeps onto his face: “I was once honored with an invitation to the esteemed 2022 Handbuilt Present in vibrant Austin, Texas!” As time continued to slip away and Coti’s slender resources were pushed to the limit, he realized that it was imperative for him to think creatively and revamp his approach if he hoped to succeed in the long run.
As he candidly reveals, he stumbled upon a salvaged KTM dirtbike swing arm and wheel at the local landfill. Coti leveraged components from the swing arm to boost the wheelbase by a substantial 2 1/2 inches, further enhancing the vehicle’s stability. Additionally, he crafted custom rear suspension units from repurposed materials salvaged from various projects within his personal workshop.
“After meticulously preparing and detailing the bike, I decided to take it aside, paint, and complete the restoration process.” He chose an underhood blue that elegantly complemented the bike’s golden accents, replacing his initial decision.
At the 2022 Handbuilt show, Coti’s RD400 cafe racer generated widespread acclaim, but its true intention lay beyond seeking praise; Reasonably, he had always wanted to own a two-stroke motorcycle that would allow him to truly appreciate the thrill of riding on the open road, and his Yamaha RD series has indeed fulfilled that wish. The newly refurbished bicycle has become his favourite mode of transportation, allowing him to embark on thrilling adventures with ease. The sound is arguably my favourite feature, but the brakes are also among the most impressive I’ve experienced. While it may not boast modern bike features, its remarkably lightweight design, tipping the scales at under 300lbs, is sure to put a perpetual grin on your face as you ride.
Notably, this RD400 represents Coti’s inaugural foray into customization, and since then, he’s been irrepressibly hooked on the process. As the next project unfolds, Kenny Roberts’ iconic RZ350 is being reimagined, leaving no room for uncertainty – this build promises to be another thrilling masterpiece.
