Yamaha’s ‘Race Developed’ series of motorcycles from the early seventies left a lasting impression on the motorcycling world. The 1973 Yamaha RD350 set the tone. At the time it was a potent street weapon that dominated the middleweight sports bike market. It was the motorcycle of choice for a generation of boy racers and in the right hands could run circles around the big inline fours of the era.
By the time the RD400 was released in ’76 Yamaha had near perfected the platform. At the heart of the bike was a 399cc, 44hp two-stroke twin. It featured capable (for the time) disc brakes front and rear, had geometry that was optimised for quick handling and could complete a standing quarter-mile in a very respectable 14.1 seconds. With a twist of the throttle, the engine revved up so fast it could easily catch an unsuspecting newcomer off guard and at full tilt it could crack the ton.
Sadly, due to stricter emission laws in the USA, and the rapid development of 4-cylinder motorcycles, the RD series lost its market appeal in the early ’80s. But for those who had experienced the thrill of riding a two-stroke RD in their heyday, the sensation was hard to forget.
Coti Sanders of Southern Maine has been riding since he was a boy. Growing up on two-stroke dirtbikes and Yamaha Banshees he developed a taste for two-stroke performance and was well aware of what an RD Yamaha had to offer. “When I was able to get a classic motorcycle, I knew it was going to be a two-stroke,” he says. “And about 12 years ago, I found this bike as a running project and traded an ATV for it.”
With no deadline to work toward Coti tinkered away on the ’76 Yamaha RD400 in his spare time with the simple goal of making it rideable. But, as is often the case, life and other projects took priority and the project was shelved. Then 2 years ago Coti decided enough was enough and it was time for his RD400 to get the attention it deserved.
Coti decided to start the overhaul at the front of the bike and work his way back to help him stay focused on each task. The process began with some serious handling upgrades.
Retrofit into the RD400 frame is a set of gold upside-down Suzuki GSXR forks. New brakes followed with a twin-disc Yamaha R1 system replacing the RD’s 46-year-old single unit. To give the new brake setup a bit more aesthetic appeal Coti machined and drilled the rotors. As for the spoked wheel they hang off, it was lifted from a Suzuki GT750 and sitting over it is a modified Yamaha TZ250 fender.
Coti was rather fond of the Yamaha RD400 fuel tank so he’s kept the original unit. But in order to smooth out its silhouette, he’s recessed the filler for a flush finish.
Next came the engine work, all of which Coti completed himself. The job involved a complete engine rebuild with larger forged Banshee pistons. Coti shaved the piston skirts to prevent them from colliding with the crank and ported the cylinders to make the most of the new additions. To complement the piston upgrade there are larger reed cages from a YZ dirtbike and Coti built the exhaust using own recipe.
“I wanted the expansion chambers to both exit on the right side of the bike,” he says. “So I made them from scratch because I’m a cheap bastard.” Cheap bastard or not fabricating a two-stroke exhaust demonstrates skill which is something Coti clearly doesn’t lack. Sitting under the engine is a steel belly pan which he of course also fabricated himself.
Mid-build things got serious when Coti was invited to display his RD400 at a prestigious event. “I was invited to the 2022 Handbuilt Show in Austin, Texas!” he says. So with time quickly running out and his budget-stretching thin Coti had to get creative with his approach.
“I found a KTM dirtbike swing arm and wheel at the town dump,” he confesses. “I used parts of the swing arm to extend the wheelbase 2 1/2 inches and added tabs for the rear shocks.” On top of that, Coti built his own rear sets using leftover parts from other projects in his workshop.
“After getting everything to fit and working I took the bike apart, painted and finished it.” When it came to choosing a colour Coti steered away from anything metallic. Instead, he opted for a Jaguar ‘underhood’ blue that harmonized with the bike’s gold details.
Coti’s RD400 cafe racer debuted at the 2022 Handbuilt show where it was met with plenty of praise, but Coti’s real goal here wasn’t chasing compliments. Rather he wanted a two-stroke he could enjoy on the street and his RD has definitely delivered. “The bike is a blast to ride now,” he says. “The sound is probably my favourite part but the brakes are also some of the best I have ever felt. It does not make the power of a modern bike but at under 300lb, it will make you smile the whole time you’re on it.”
Surprisingly this RD400 is fact Coti’s first custom project and he has now been bitten by the bug. Next up he’s planning a Kenny Roberts style RZ350 and we have no doubt it’s going to be another humdinger of a ring a ding dinger.