Synchronicity: Doc’s Chops Builds a Yamaha Seca 900

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1983 Yamaha Seca 900 Custom
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1983 Yamaha Seca 900 Custom
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1983 Yamaha Seca 900 Custom
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The Seca wears Works Performance rear shocks built to Greg’s specifications. The rearsets are from Raask, and the switchgear and levers are Yamaha R1 components.
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The tail section is a stock Yamaha 550 Seca piece, but Greg fabricated a steel seat frame to take the pad and cover.
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The bike uses 43mm front forks and dual discs from a FZR1000.

1983 Yamaha Seca 900Custom
Claimed power:
97hp @ 9,000rpm (est.)
Top speed:
853cc air-cooled DOHC inline four, 67 x 60.5mm bore/stroke, 9.2:1 compression ratio
Weight: 453lb (205kg)
Fuel capacity/MPG:
3.9gal (15ltr)

Fans of synchronicity will appreciate this: Three years ago close to this very day, I sat in front of this very computer and pounded away at this very keyboard. My assignment was a piece about Greg Hageman, aka Doc’s Chops, and a 1982 Yamaha Virago 920 he’d transformed into a stunning café racer for Mike Martens of Kansas City, Missouri. The Ugly Ducklingran in the 2012 May/June issue of Motorcycle Classics.

Ever since his 2011 appearance in the second season of Café Racer TV, Greg and his Florida-based shop Doc’s Chops have become well known for building road-ready custom Viragos, along with parts and pieces to help others customize their own bikes. It was Greg’s TV debut that brought him to Mike’s attention.

Mike was blown away by Greg’s eye for detail, and he wondered if Greg would be interested in building a shaft drive Yamaha café racer based on the transverse 4-cylinder Seca platform. Their conversation went in circles, and instead of the Seca that Mike wanted, Greg ended up building the 920 Virago that was featured in the story.

The Seca’s draw

“My first bike was a 750 Seca that I bought when I was 16,” Mike says of his interest in the model. “I bought it in 1982 in Dubuque, Iowa, from a guy who’d lost his job. When I first went to look at it he wanted $2,500 and I only had $1,500. I didn’t even make him an offer.

“Later, I saw the ad again, and I went back. I was the only one who’d expressed interest, and I now had $1,600. He took the cash, and I rode it home. I kept it for quite a few years, rode it daily, and took many trips on it. The Seca made me a Yamaha man, and it made me appreciate shaft-drive motorcycles.”

Beyond Mike’s obvious nostalgia for his first motorcycle, Yamaha’s Seca lineup — known as the XJ series — offers interesting platforms just ripe for one-off builds.

Yamaha produced several different versions of the XJ from 1980 to 2008, from 550cc to 1,300cc. All the XJ models feature inline 4-cylinder engines, but not all of them are highly considered. “Some of the early Secas did not age very well,” Mike opines, leveling his aim at the models equipped with a square headlight. “They’re part sport bike in their stance, and part cruiser with a lower seat. I guess they’re something of an acquired taste.”

Although completely happy with Greg’s café racer Virago, it wasn’t the Seca that he originally wanted, and Mike wasn’t prepared to give up on the dream. In fact, after taking delivery of the café racer Virago, he went shopping and found a 1983 Yamaha XJ900R Seca for sale on eBay. A model that was available for only one year in the States, the Seca 900 is something of a rarity here. It was, however, a prolific model in other world markets.

“The Seca I found was a low-mileage motorcycle, but it had been somewhat neglected,” Mike says. “I bought it, and just put it in storage. And I kept talking to Greg. He said he would eventually build the Seca when he was in between some of his other builds.”

Waiting game

While he was waiting, Mike shopped eBay for parts that he thought might work in a custom application. He bought numerous tanks and tail sections, all from other Yamaha models of the 1970s and 1980s. For a few months, the UPS delivery man was a fixture at Mike’s door. Tanks originally found on RD400s, XS500s and XS750s, as well as one from a XJ550 Seca all went on Mike’s shelf, together with numerous Yamaha fork components.

In anticipation of delivering the bike to Greg for his deft custom touches, Mike took the Seca to Eric Bess at Flying Tiger Motorcycles in Maplewood, Missouri. It was Eric’s job to check, detail and tune the engine. “It was a healthy motor with perfect compression,” Mike says. “Eric took it out of the frame and tore it down to the point where it could be painted and polished to stock Yamaha specifications. Anything originally painted black was painted black, and anything polished was polished. Eric put a ton of labor into detailing the engine and the polishing, [it’s] just incredible. I knew when Greg saw it he’d feel the bar had just been raised.”

Although he left the engine mostly stock, Eric installed a set of Mikuni RS36 flat slide carburetors originally intended for a Yamaha FJ1100, along with SuperTrapp Megaphone mufflers on stock Seca 900 header pipes.

Then, in early June 2014, Greg finally called. “I loaded up the trailer with the bike and all of my accumulated parts and drove to Greg’s in Florida, and spent two days in his garage,” Mike says. The first day, Mike helped strip away the fairing, body panels and other extraneous parts from the Seca 900. Greg was busy tuning a Harley-Davidson Road King for a friend, so while Greg was otherwise occupied, Mike would drop a different tank from his horde of parts onto the bike’s backbone to see how it looked.

“Greg would quickly look up and say ‘No’ to most of the tanks; until I put on one from a 1982 Seca 550, and propped up the tail section, too. He looked up and said, ‘That’s the one,’” Mike says. That same day, Greg installed the forks, sourced from a Yamaha FZR1000. Mike was pleased with their progress. “I thought we’d hit a home run, but Greg reassured me there was plenty of work ahead to make it all happen.”

His two days up, Mike drove home and left Greg to finesse the build. In order to make the Seca 550 tail section fit the 900, Greg cut away a portion of the Seca 900’s rear frame. Next, he bent and welded together a new subframe, attaching it so that the top rails were in line and level with the bottom of the Seca 550 tank. The Seca 550 tail section was left completely stock, but Greg fabricated a steel seat frame to take a pad and cover. The gas tank mounting points had to be moved on the frame, and there was some reshaping required on the bottom of the tank itself. “I used a hammer,” Greg says. “It wasn’t a bolt-on modification, but it wasn’t too bad, either.”

Keeping it period

Greg and Mike appreciate period-looking forks. The FZR1000 front end had already been worked over with Progressive springs and Race Tech Gold Valve emulators. With 43mm stanchions holding the stock Seca 900 fender, the forks are beefy, yet timeless in appearance — especially with the XS650 front hub bolted in place. Dual discs are stock FZR, and to get them to fit the hub Greg had adaptors machined to suit.

The Seca 900 originally came with mag wheels, but one of Greg’s signature modifications is installing wire spoke wheels on shaft-driven Yamahas, something the factory did only on select models. The tricky part now is finding a donor Yamaha rear hub to make the conversion, as the particular spoke hub/shaft drive parts he uses are becoming rare and expensive. Fortunately, Mike had purchased an extra hub three years ago and it was in his stash of parts. After detailing the hub, Greg laced it to a 4.25 x 17-inch Excel alloy rim, using stainless steel spokes from Buchanan’s Spoke & Rim. The front wheel is a 3.25 x 17-inch hoop, and both are wrapped in sticky Continental rubber.

Dual shocks from Works Performance, built to Greg’s specifications, suspend the stock swingarm. Keeping to theme, Greg added Tarozzi clip-on handlebars and Raask rearsets. The switchgear and levers are Yamaha R1 components, and the headlight is an aftermarket, bolt-on piece. The instruments are from Acewell.

Once Greg had finished his modifications, he tore down the mocked-together bike and sent the frame, components and body panels out for final finishes. The chassis and its pieces were treated to black powder coat, while the tank and tail were given to Moe Roberts of Moe Colors in Tampa, Florida, for a traditional red and white Yamaha Seca paint scheme. Except, that tradition has been updated with the addition of a little metal flake and pearl to help catch the sunlight, and raised Yamaha badges were traded for hand-painted lettering.

“I’ve been nicknamed the ‘Virago Whisperer,’” Greg says, “so it was nice to do something different. The Seca 900, from the factory, was set up as a sport-touring bike and it was a decent enough design to begin with. I just made a sportier version, shortened it up and tightened it up.” A stock 1983 Seca 900 tipped the scales at 534 pounds with a full tank of gas, but Mike’s café version has shed some weight, coming in at 453 pounds.

Both Greg and Mike say it’s a blast to ride. “It handles great,” Greg adds, “and it’s got a lot of top-end performance; past half-throttle it’s like setting off dynamite. Open it up and the inline-four really starts to sing. I’m glad I built it for Mike, but I don’t think I’m going to make a habit of building 4-cylinder motorcycles — I still prefer singles and twins for their simplicity.”

And that brings us back to synchronicity. Mike would now like Greg to construct a café bike using a modern Yamaha SR400. It would, he says, complete a trilogy of “Hageman Originals” in his garage.

Perhaps in three years’ time I’ll be writing a story about the build. MC

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