The Yamaha XJ550 Seca

Tomorrow’s classics: 1981-1984 Yamaha XJ550 Seca.


| May/June 2012



Yamaha XJ550 Seca

Yamaha had the café racer set in mind when it designed the new-for-1981 Yamaha XJ550 Seca.

Yamaha XJ550 Seca
Claimed power:
50.46hp (rear wheel) @ 10,000rpm (period test)
Top speed: 110mph
Engine: 528cc air-cooled DOHC inline four
Weight: 424lb (with half-tank fuel)
Price then/now: $2,529/$1,300-$2,700

If the test of a good design is longevity, the XJ engine line must be considered one of the best. In continuous production from 1980 to 2008, the air-cooled, eight-valve DOHC inline four has been available around the world in 400, 550, 600, 650, 750 and 900cc form.

The first XJ was the 650, launched in 1980, with the 550 joining it a year later. More than just a 650 on a diet, the Yamaha XJ550 Seca was essentially all new.

Unlike the 650, which used gears for primary drive, the Seca 550 crankshaft drove a hydraulically tensioned Hy-Vo chain to a jackshaft carrying the clutch and alternator. The jackshaft provided gear drive to the 6-speed transmission, which, unlike the stacked shafts of the 5-speed 650, was laid out horizontally. And while the 650’s final drive was by shaft, the more sporting 550 used a chain. A conventional steel tube frame and swingarm ran on cast alloy wheels fitted with a single front disc brake and rear drum. Also conventional was the non-adjustable front fork, with dual shocks (adjustable for preload) at the rear.

The novel cylinder head design featured Yamaha’s YICS induction control system. Cast into the head was a second, smaller set of intake ports connected across all cylinders, so that each cylinder received two simultaneous charges of fuel/air mixture — one from its own intake port, and one at much higher velocity from the YICS “sub-intake” port positioned just above the valve head. The idea was to create extra swirl in the combustion chamber and therefore more efficient combustion. Did it work? The Seca 550’s test fuel consumption of 53mpg suggests it did.

The Yamaha XJ550 Seca was also well-equipped, with features you’d expect only on bigger, costlier bikes: self-canceling turn signals; a clutch/neutral electrical interlock that prevented the Seca being ridden away with the sidestand down by killing the engine if you shifted into first before lifting the stand (routine now, but new at the time); an adjustable front brake lever; and a warning light that showed low oil level rather than low pressure. The idea was that the owner got a warning to top up the oil in the wet sump before it got so low that oil pressure was lost — a potential engine-saver.

freetoride81seca
9/5/2014 12:33:28 AM

I bought the first 550 Seca in south FL. in December of 1980 from Larry Seiples Yamaha. I was in 12th grade and a greenhorn. I didn't even know how to ride...but I soon learned. It was my only source of transportation for over the next two years and 22,000 miles. I went to my first bike week in Daytona in the spring of 1981 with some friends who also had bikes...we had a blast and slept on the beach too. I sold it after two years to a good friend... we're still friends today. It was a great bike and very reliable. There's nothing like your first bike...😃😃. I'm planning to get another classic soon...a 1982 Seca 550....Wooooooohooooo. Be safe out there and happy trails. Peace!


westcoaster
10/10/2013 3:44:04 AM

hi everyone, I am trying to find some plastic side plate covers for my 1980 Yamaha 550 seca , can anyone help ? bennettbrendan@ymail.com is my email thanks again ( Brendan )


westcoaster
10/10/2013 3:43:59 AM

hi everyone, I am trying to find some plastic side plate covers for my 1980 Yamaha 550 seca , can anyone help ? bennettbrendan@ymail.com is my email thanks again ( Brendan )


westcoaster
10/10/2013 3:43:56 AM

hi everyone, I am trying to find some plastic side plate covers for my 1980 Yamaha 550 seca , can anyone help ? bennettbrendan@ymail.com is my email thanks again ( Brendan )


phillip mcmurran
4/21/2012 3:36:42 PM

I bought a 82 XJ550RH in 1986 new for $1800. What a deal! There were a bunch of left-overs and I got a deal. I put 22,000 street miles on it then raced it with WERA in D production class from 1989-1991. In the article you wrote that it had shim-under-bucket followers. I don't remember it that way, I thought that they were shim-over-bucket. There was a two piece tool to get the shims out. Anyway, good article keep up the good work






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