During the mid-70s, the Yamaha RD400 was the ultimate middleweight sport bike. Known for its explosive power and lightweight frame the two-stroke legend was an evolution of the RD350. It boasted a slightly bigger engine, a rear disc brake and more refined handling. The RD400 quickly became a favorite among racers and enthusiasts alike, revered for its ability to be both a street-legal machine and a formidable competitor on the track.
Thanks to seasoned racer and moto enthusiast, Armen Manougian, one of these iconic bikes has been brought into the 21st Century. Armen has a long history of working on bikes, starting with his first, a YSR50 when he was in the 10th grade. With an automotive passion that has grown over the years, Armen eventually established his own workshop, Allstar Auto Center. While the shop mainly caters to cars, he’s always reserved space for working on road race motorcycles, a testament to his love for the craft.
“The bike was originally owned by John Lau who is the distribution manager at Yoshimura and has worked there for over 40 years!” says Armen. “John had built the bike to road race and teamed up with a young rider named Windell Phillips (who went o to own Lockhart Philips USA). The bike was raced at Willow Springs International Speedway and after losing interest they turned it into a canyon carver and would often take it up in the Los Angeles hills at the famed Mulholland Canyon on the weekends. ”
By 2016, the RD400 had been sitting idle in John’s garage for several decades. Faced with moving to a smaller place, John asked his good friend Russ Norman what he should do with the bike. Russ, who was already knee-deep in his own custom projects, suggested they give it to Armen, knowing he would do something incredible with it. As it turned out, Armen had long wanted to build a classic cafe racer but had never settled on the right project—until this one fell in his lap.
After acquiring the bike, Armen stalled the build while other aspects of life took priority. But eventually, 5 years later, prompted by Russ’s relentless encouragement, he dragged the bike out, dusted it off, and got to work.
“The bike’s history made it a great story, due to its racing pedigree. Most cafe racers have never been raced so it sparked some interest in me, especially with my racing background,” Armen says. “My vision for the bike was to implement modern tech, race track pedigree, and classic style into a motorcycle that would catch the essence of the classic RD400 look but with modern technologically advanced improvements found on current racing machines.”
“Upon examining the bike closely I noticed the heads were different,” Armen explains. “Russ had told me John had spent a fortune back in the day on ultra rare water-cooled heads made by Revco. These heads simply replaced stock heads and came with a tiny radiator. The coolant flows by a process called thermo-siphon so there is no need for a pump. Also, I noticed the rear wheel was a very rare 18” Morris Mag wheel, while the front was a stock alloy Yamaha wheel. ”
With such premium parts already in place Armen continued the theme with the suspension. Rather than fitting a complete late-model front end that would likely throw out proportions, he opted to retain the original RD400 forks. However, internally, things are far from stock. Armen machined the dampening rods so they could accept gold valve emulators from Racetech and machined a custom adjustable shim stack for pre-load. Mark Atkinson from Speed of Cheese Racing in Utah made the air-charged fork caps. The custom triple clamps made by Cognito Moto are set back 10mm making the fork-to-stem offset 35mm, as opposed to the stock 45mm and there’s an Ohlins dampener under the headlight. For the rear suspension, Armen contacted Mike Wheeler at Kyle Racing USA to request a set of custom Ohlins rear shocks.
Mark Atkinson (Speed of Cheese Racing) was also instrumental in the design of the RD’s new swingarm that extends its footprint by two inches. The intense level of customization continues with titanium axles, custom brake brackets, and a one-off paint job by Matt Polosky that paid homage to both Yamaha’s racing heritage and Armen’s own racing colors.
This bike’s engine received just as much attention. “During all the frame and prep work I had the engine completely torn apart. First thing was to gut the entire engine and send most of the internals off to Scott Clough of Scott Clough racing,” Armen recalls. “Scott is a legendary former Southern California. road racer and RD engine specialist. He ported the cylinders and reed cage to house V force 4 carbon Reeds. He honed the cylinders and got a new set of pistons and built the crank using ceramic bearings.”
To complement Scott’s work, every internal part was polished and cryogenically treated for durability and performance, with the entire engine assembly taken care of by Gus Christensen, another seasoned expert. With the engine built, Armen added an intake consisting of machined manifolds by Chariot and a pair of 32mm Mikuni flat slide carburetors. As for the exhaust, it was fabricated by JL exhausts and mounted using spigots and flanges by Mark CNC to match the larger exhaust porting.
The bike’s electronics have been modernized using a Motogadget M-Unit Blue, allowing for keyless start, app connectivity, and a simplified wiring harness. A custom dash housing a Cognito Moto GPS-driven tach/speedo setup was fitted, and even the lights were updated with Motodemic’s adaptive headlight system.
Armen’s attention to detail extended to the brakes, where he’s opted for dual Brembo calipers. These were installed by custom machining the forks to accommodate the setup while maintaining a clean, symmetrical look. Even the wheels, which are now both Morris Mags thanks to a generous donation from Russ’ friend Howard Monise, have been coated in Spanish Gold and fitted with ceramic bearings. Infact there are so many custom details on this bike it’s impossible to cover them all, but you can rest assured nothing was done without a clear defined purpose.
This project was not just about the bike; it was a tribute. Throughout the build process, Russ, Armen’s friend and mentor for nearly 30 years, was there – pushing him to get it done, sharing ideas, and reminiscing about their racing days. Tragically, Russ was battling bone cancer, something he kept hidden from most.
The bike, completed just before Russ’s health took a turn for the worse, won Best of Show at the 2 Stroke Extravaganza in Southern California. Russ passed away 80 days later, but not before seeing the RD400 he had helped inspire. After hearing it roar to life, Russ told Armen that it was the best RD400 he had ever seen. A lasting memory of Armen’s good friend is forever immortalized by this incredible motorcycle.
