The Yamaha XJ550 Seca

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

  • Yamaha XJ550 Seca
    Yamaha had the café racer set in mind when it designed the new-for-1981 Yamaha XJ550 Seca.
  • Kawasaki GPz550
    Kawasaki GPz550
  • Honda VF500F
    Honda VF500F

  • Yamaha XJ550 Seca
  • Kawasaki GPz550
  • Honda VF500F

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.

3/17/2021 12:29:58 PM

Good power, adequate handling - sh*tty brakes ! I tried roadracing one and gave up after 2 attempts. My year older RD400 was a better track bike by far.

Matty McMatty
6/17/2019 4:38:33 PM

This was my first bike! An older co-worker used it as an everyday bike, and one day he expressed a willingness to sell it at a future date. Once I heard that, I begged and pleaded and cajoled him for months, LOL. My parents ended up gifting me their old 1978 Toyota Corona wagon and I sold it for a few hundred to get the loot to buy the bike. My co-worker even had a matching helmet for it! I bought it in the spring of 1991, my Senior year in HS. I still remember that I stayed home the Monday after I bought it, but made sure to show up to the local pizza place where all of students ate lunch to show it off and do a burnout, LOL I thought I was the coolest thing on 2 wheels back then! I still remember that it had an aftermarket Supertrapp 4-in-1 exhaust pipe, but was otherwise stock. That was my only source of transportation over the next 2 years. Always reliable. The only issue was cold starting it in the dead of winter required a push start. So many memories. I feel honored to have owned such a classic bike.

3/23/2019 4:47:04 PM

Bought my 81 maxim 550 last year as a budget bike to fulfil my need for two wheels, fully intending on getting something “better” this year. I liked it so much I spent the winter customizing and painting it. I still want something bigger and more comfortable for touring, but I think I’ll keep this bike around!

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