Without the single-cylinder motorcycle engine, biking might not exist. It somehow fuels the most popular motorcycle model in history, numerous dependable modes of daily transportation, and numerous lawnmowers.
Single Cylinder Engines: Pros
- Simple designs with fewer moving parts have lower production costs and simpler maintenance requirements.
- Two-stroke variants supplied high power.
- Versions with four-stroke engines provide strength, torque, and versatility.
Single Cylinder Engines: Cons
- Due to their high pollution levels and limited power bands, two-stroke engines are now used in scooters and learner models.
- Compared to their two-stroke or multi-cylinder counterparts, four-stroke single-cylinder machines have less power.
- They experienced significant vibration until balancer shafts were added to current motorcycles to lessen the issue.
Single Cylinder Motorcycle Engines: History and Design
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Light and Simple
A single-cylinder engine’s straightforward, compact, and lightweight bike design makes it ideal for motorcycling, especially in earlier times and, more recently, for off-road racing competitions. A multi-cylinder engine with fewer cylinders is easier to cool than one with more cylinders because of the simpler design, making maintenance and repairs easier.
Only the lower-performance singles and V-Twins on current bikes are still completely air-cooled. Because the piston completes a power cycle (up and down) as the crankshaft rotates once in a two-stroke engine, you need fewer moving components and generate more power for capacity and weight.
However, if you make a four-stroke version with a double-rotated crankshaft, you’ll have a more fuel-efficient motor with strong torque and dependability. For this reason, single-cylinder engines were so prevalent in the first 70 or 80 years of cycling.
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Thumpers
However, single-cylinder engines have an intrinsic capacity restriction, so most are at the opposite end of the spectrum, around 125cc. You will rarely see any beyond the 600cc–700cc range.
The weight pushed up and down with each crankshaft spin increases with cylinder size. Because of the bigger power bursts and increased overall vibration caused by this, larger singles are known as “thumpers.”
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Evolution
As the 1900s began, the largest motorcycle manufacturers started with single-cylinder designs. The first iterations were usually four-stroke models made by companies like BMW, Norton, Triumph, Harley-Davidson, and others.
There is a significant possibility that it is one if it appears like someone has fitted an engine into a bicycle frame. That persisted as biking advanced into the modern age and the British manufacturers’ post-war Café Racers.
One hundred years after it all started, the current generation of Moto 3 race bikes continues to compete at the top levels of motorcycle racing. This is done with a single-cylinder engine. Additionally, motocross and off-road bikes still use one or two-cylinder engines, depending on the market.
So why aren’t all motorcycles singles? They have some significant drawbacks.
Four-Stroke Singles Engine
The Benefit Of Four Strokes
Four-stroke singles have increased while two-stroke singles have decreased. More than 100 million Honda Super Cub models in the 49-124cc range have been sold since. The BMW G650 series and the Suzuki DRZ400 are two well-known examples that highlight the attributes of a four-stroke single nicely. They both use four-stroke engines, which provide a far greater power range than two-strokes, especially at low revs.
With either a DR-Z400 or a G650GS, you can ride slowly along green lanes all day, picking up your bike after crashes, and yet be certain to reach your goal eventually. The KTM 690 Duke, the Yamaha MT-03, and the Honda Monkey are modern examples of 250cc four-stroke single KTM engines used in the Moto3 championship.
With many four-stroke singles, the more moderate output can also be used more effectively due to the smoother power delivery. The KTM 690 Duke produces 72.5 horsepower and 120 mph, which is acceptable for a middleweight motorcycle. But it’s also comfortable, simple to use, and to ride. A feature it shares with the smaller Yamaha MT-03 and the extremely odd-looking BMW F650CS.
The single-cylinder four-stroke choice, like the Honda CRF250 Rally, is always a good choice if you’re looking for a practical middleweight or green lane bike.
Rare Models
The Ducati Supermono is one of the most unique single-cylinder vehicles ever produced, so if you have a sizable budget, you might want to look to compete in the European Supermoto Cup, which World Superbikes back, only 65 bikes were produced between 1993 and 1995.
The Pierre Terblanche motorcycle, which had a top speed of 141 mph and weighed just 121 kg, might have influenced modern Moto3 race bikes. These bikes feature 250cc single-cylinder engines with 55 bhp and top speeds of 152 mph at 14,000 rpm.
Two Strokes Singles
What Caused the Demise of Two-Stroke Engines?
Due to its relative power, the straightforward, two-stroke, single-cylinder engine gained popularity in road and dirt racing. But since the 1990s, a few compact scooters and mopeds have vanished. Two-stroke engines are declining due to several factors.
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A Challenge To Ride
Because the power output is always focused on a relatively small portion of the rpm range, maintaining a reasonable speed on your motorcycle requires constant effort. As you wait for the revs to increase, other riders will be edging away from you outside the power band.
Some people find it enjoyable, especially riding on a racecourse or dirt track. Despite the wonderful sound of a furious wasp imprisoned in a biscuit tin spinning at 15,000 rpm, it’s more of a headache on the road.
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Emissions
The technical justification for using a gasoline/oil mixture for fuel is total cylinder lubrication loss. Additionally, it explains why a blue smoke cloud appears after every two strokes. Pre-mix does not appeal to everyone, and as environmental issues gain importance, manufacturers have concentrated on multi-cylinder engines.
When you consider the possibility of an engine locking up, you can see why riders of two-strokes feel compelled to keep their clutch lever covered at all times.
