Retrospective: 1979-1992 Yamaha QT50 Yamahopper

1980 Yamaha QT50 Yamahopper
1980 Yamaha QT50 Yamahopper. Owner: Kathleen Daly, Atascadero, California.

Looking in Cycle magazine’s “1980 Buyers Guide,” the Motorized Bicycles section has more than 20 bikes listed. Most of them are a hair under 50cc, making them eligible in many states for young teenagers without driving licenses. The Yamahopper blurb reads, “Despite its low price the ’Hopper is equipped with turn signals, Autolube oil injection, solid state CD ignition, front and rear luggage carriers, and drum brakes at each end.” The magazine does not list the “low price,” but the owner of this 1980 model, who bought it new, remembers paying $600 for two, one for her and one for her husband.

1980 Yamaha QT50 YamahopperThere was a serious energy crisis in the 1970s, with gas prices going way up, and many motorcycle manufacturers thought they could take advantage of this by producing small motorbikes that not only sipped fuel, but also cost very little. Instead of driving that big gas-guzzling V-8 to the market on a sunny day, one of these 135 mpg vehicles would do—presuming one put a big basket on the luggage rack to hold the groceries. This was a no-pedal (noped) machine, with fixed footrests and a kickstarter.

The chassis begins with a skeletal frame, officially labeled as a “steel tube underbone, as simple as they come.” A well-bent tube came down from the steering head and stayed low for step-through efficiency (especially for a lady in a dress), then rose up to support the seat. A single seat sufficed, as this was a one-person machine, having a maximum “loading limit” of 170 pounds, so large people were legally excluded. An unsophisticated telescopic fork comprised the front suspension, with a rake of 25 degrees, trail of almost 3 inches. The steering head had 26 individual ball bearings in each of the two races—do please be careful if ever dismantling the front end. At the back an oil-damped shock absorber went up to the bottom of the seat from the single-sided swingarm, which also housed the drive shaft. Both front and rear suspension had less than 2 inches of travel, indicating that this machine was intended for smooth surfaces like well-paved streets.

1980 Yamaha QT50 YamahopperBoth wheels were 14 inches in size, with small single-leading-shoe drum brakes operated by hand levers, right side for rear, left for front. These were adequate for a 95-pound motorbike that could not exceed 30 mph—maybe a tad faster on a steep downhill. Axle to axle the wheelbase was a brief 41.3 inches, and the turning radius was a minimal 5 feet. Getting this baby pointed in the opposite direction was easy to do.

1980 Yamaha QT50 YamahopperThe photos show the little powerplant bolted beneath the frame. The 49.9cc single cylinder was almost square, with a bore of 40mm, stroke, 39.2mm. Compression ratio was a modest 6:1. The carburetor used was a Mikuni VM12SC, running fuel through a reed valve, an efficient and inexpensive way of allowing the fuel mixture to enter the crankcase as the piston rises, and then closing off the intake as it descends. Should anyone ask what the valve’s bending limit is on the QT50, it is 0.8mm; potentially useful knowledge when a barroom of Yamahopper owners are making bets. Yamaha’s Autolube system made sure the gas and oil mixture was as close to perfect as possible. The company had been using this remote oil system in racing bikes in the early ’60s, but the first use on a street bike was in 1964, with much acclaim. First, it reduced the smoky exhaust seen on most two-strokes, and second, ended the messy mixing of oil with gas in the U.S. Europe, with lots of two-strokes, had special two-stroke pumps at the gas station, where the rider just dialed in the right amount of oil and the job was all done. The Yamahopper’s oil reservoir held 0.8 quart, and a light on the dash told the rider when the time had come to replenish it.

1980 Yamaha QT50 YamahopperThe footpegs had the rider’s feet on both sides of the cylinder. Narrow fenders gave small protection to the rider, but the presumption was that not many people would ride this on a wet day. Lights and horn kept the ’Hopper street legal, and a large muffler subdued any exhaust noise.

Starting was quite easy, with a small kickstarter on the left side. First, open the petcock on the 0.6-gallon gas tank, good for almost 100 miles. Since the bike was meant for hopping around town, long distances were irrelevant. Then turn the ignition key, up on the small dash, to ON, activating the CDI (Capacitor Discharge Ignition), move the “starter lever” over on the left grip to full choke, and kick. The magneto should fire the spark plug with just one or two pushes. Let it warm for a few seconds, move the lever back to the run position, and take a seat.

1980 Yamaha QT50 YamahopperTwisting the throttle sent the power back through a wet centrifugal clutch and single gear. This clutch unit had its own oil supply; the four-stroke kind that the manual said should be changed once a year. Slightly messy, but probably few owners did it. A right-angle bevel drive sent the power into the drive shaft, intended to minimize messy maintenance, and another right angle went into the rear wheel.

Off you go! But not very fast. The manual warned the rider that low-speed overtaking could take more than 15 seconds, while a high-speed pass was “not capable.” Also, the “climbing capacity” was only 9.6 degrees, so obviously not very suitable for a place like San Francisco. Los Angeles, fine; Manhattan, fine. Any flat town, fine.

And undoubtedly some brave soul did ride one of these ’Hoppers from coast to coast.

3 COMMENTS

  1. This was my first vehicle. I got one when I was 14 because in Iowa you could get a moped license at that age. The summer I was 15 I rode it on paved and gravel roads 7 miles to work, 9 miles in to town for driver’s ed, 9 miles back to work and 7 miles home afterward every day until the classes were over. I always wanted a blue one but the day we went to buy it they only had red.

  2. I got 1980 yamahopper too! I got it as a 20th birthday present. Sat outside for 3 years with open weather meaning it was litter ally outside. It was a junker nearly, but anyways I fixed it up July 5th of this year and after a few major fixes I got it street legal and its the best thing for me in a 4.5 mile direction of everything I need. Store, gas, work, home, beach, friends etc…well its fun. Its a cutie and its very reliable. I’m 23 and it sat in my garage when I got it. After replacing the carb and getting a battery for it it started up in less than 5 minutes!!! I was like wow! Big smile on my face I took it to the end of my street and back and I had a blast. Minor maintenance and it shows me its capabilities as well as my problems that need attention so I recommend this bike because it cheap and reliable!

  3. i got one for free its been sitting behind some dudes barn for 20 years, it has 2168 miles on the odometer and the motor was locked up solid, i got it unstuck but the d*** thing wont start, turns out that 1980 coil is garbage and the oil pump don’t work.

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