The Smallest Displacement Twin-Cylinder Engine Ever On A Production Motorcycle

Small-displacement motorcycles are having a moment right now — but none of today’s peppy commuters can claim what a 1972 Yamaha quietly pulled off decades ago. While modern mini-bikes typically lean on a single-cylinder 125cc motor, Yamaha once built a 100cc parallel-twin — yes, two cylinders, each displacing around 50cc — and sold it as an everyday road bike. The result was the LS2 100, one of the most unusual and endearing machines ever to roll out of Japan.

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This two-stroke Yamaha motorcycle was all about “fun”. The performance and dimensions were modest, just like the engine size. But browsing various motorcycle forums that have mentioned this rare classic Yamaha, the words “smoothness” and “explosive” were often used together in one sentence.

You might wonder how a 100cc city bike can be “explosive.” Well, if there’s one thing that Japanese car and motorcycle makers have taught us, power and torque figures are only a small part of the “fun” formula.

Here’s a deeper look at the smallest twin-cylinder Yamaha motorcycle ever built for the road.

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1972 Yamaha LS2 100: A Retro Motorcycle With A Pint-Sized Parallel-Twin

Engine Size: 97cc (5.91 cu-in)

Twin-cylinder motorcycles — parallel or V-Twin — evoke a sense of sportiness or big-bike appeal, respectively. The most celebrated parallel-twin in the middleweight category is Yamaha’s own CP2. The big-bike V-Twins have established their dominance with the likes of Harley-Davidson, Indian, and every other 1000+cc cruiser you see on the road.

The point is that twin-cylinder motorcycles aren’t at the bottom of the performance engine type pyramid. Want performance? A parallel twin checks the box. Want road presence and rumble? A V-Twin checks the box. But in 1972, Yamaha built a parallel-twin city commuter with the LS2 100. Its two-stroke architecture gave this tiny parallel-twin a heightened level of mechanical refinement — though it was nowhere near the “performance” criteria that parallel twins fulfill today.

While the definition of a “fun” motorcycle today is heavily dependent on performance figures for many, a Reddit user (A40) aptly summarized why the Yamaha LS2 might give you a wider grin than any high-capacity sports bike.

‘Kick start’ it with two fingers once it was warmed up. Flat out, up and down through the gears, cornering to its limits .. and never breaking any traffic laws. The best 🙂

Tell us of any modern motorcycle that can be taken to its absolute limit on a grocery run. This is exactly why small and peppy motorcycles like the LS2 deserve a comeback.

Yamaha marketed its peppy 1970s city bike as a “town and country runabout”. The LS2 100 may have an engine smaller than the minimotos offered by the likes of Honda and CFMoto, but it was a fully capable road bike with 18-inch wheels, a five-speed transmission, and two separate dials for the speedometer and tachometer.

Despite its compact footprint, the styling is gorgeous, with loads of chrome. The retro design elements have aged like fine wine, and the fact that it was produced for just one year makes this tiny Yamaha a very rare motorcycle today.

Yamaha LS2 100 Two-Stroke Engine Specs

Yamaha LS2 100 Has A Top Speed Of 69 MPH

The LS2 Rapidly Accelerates To 40 MPH

The LS2 100’s tiny form factor makes it quite the nimble motorcycle. Its single-digit horsepower rating is not eye-popping. But pair that humble power figure with a smooth and quick-revving two-stroke motor and a curb weight of just over 200 lbs, and you have a recipe for pure, unadulterated fun.

The Yamaha LS2 has a top speed of 69 mph, but reaching those numbers is a stretch. Many owners have noted that it accelerates “rapidly” to 40 mph, which is the sweet spot for this peppy Yammie. That’s a vital piece of information for any daredevil planning to tour on this retro machine.

The LS2 Yamaha Two-Stroke Bike Was Sold For Just One Year

Bonhams

Despite being such a hoot, the Yamaha LS2 100 two-stroke was manufactured for just a single year. It was a motorcycle explicitly developed for the US market, created to meet the growing demand for affordable and fuel-efficient transportation during the 1970s energy crisis.

But Yamaha hadn’t fully accounted for the competition from within its own lineup. The 1970s Yamaha 125 twin was a motorcycle with a similar footprint that produced roughly five more horsepower at only a marginally higher price. The 125 effectively cannibalized the LS2 100’s potential audience and cut short its future.

How Much Is The Rare Yamaha LS2 Worth Today?

Used Price Range: $575 – 3,000

Mecum Auctions

The 1972 Yamaha LS2 is a rare classic motorcycle, having been sold for just one year in the US. In fact, we came across just three sales of this Yamaha from popular auction websites. The cheapest recorded sale was from Bonhams, which fetched $575.

The most expensive sale came from H and H. A UK-import LS2 sold for close to $3,000. To put that in perspective, that’s well above the entry price of many brand-new small-displacement bikes on the market today.

Chances of an LS2 Yamaha 100cc two-stroke popping up for sale are slim — we suspect that the people who own one truly value what it delivers in terms of riding experience and sheer fun.

BONUS: The Absolute Smallest Twin-Cylinder Motorcycle Engine Ever Made

Hint: A Wild Honda Race Bike That Revved To 21,500 RPM

If we remove the “production” qualifier from the conversation, there’s an even wilder motorcycle to consider. The 1960s Honda RC116 is a baffling race bike powered by a 50cc twin-cylinder engine. It began life as the RC110/RC111 in 1962 with 9.5 horsepower peaking at an insane 14,000 RPM. By the time the RC116 arrived, Honda had effectively super-saiyan-ed this petite 50cc twin.

The most powerful version of Honda’s air-cooled twin-cylinder 50cc unit produces over 20 hp at an insane 21,500 RPM and has a top speed that puts many modern middleweight sports bikes to shame. The Honda was a successful race bike, winning three of the six races it entered.

Honda’s 50cc monster couldn’t stay long in the spotlight, as the manufacturer officially withdrew entirely from motorcycle GP road racing in 1968.

Honda RC116 50cc Racebike Engine Specs

(Specs sourced from Motospot-oldnews and Bart Via YouTube Comments)

Sources: Mecum Auctions, Bonhams, H and H, Bikez, Yamaha Motor USA, Reddit, Moto-Spot-Oldnews