Motorcycle engines: design, principle of operation, technical characteristics

A lot of articles have been written about car engines, there is a lot of different information. There are not so many articles, diagrams, or descriptions about motorcycle engines. Let's try to fill this gap. There are quite a lot of motorcycle enthusiasts. Among them there are also beginners who still know little about the design of internal combustion engines in motorcycles.

Motor vehicles are predominantly equipped with two-stroke, four-stroke, rotary and boxer engines. The latter are not so widespread, but certain manufacturers use them.

General structure and principle of operation

Motorcycles are equipped with units in the combustion chambers of which the thermal energy released from fuel combustion is converted into mechanical energy. The piston of a motorcycle engine receives the energy of combustion products, after which reciprocating movements begin. Thanks to the crank mechanism, the crankshaft rotates. These are the main components in the internal combustion engine.

The crank mechanism is practically no different from a car engine. The piston group is also not much different. The piston here has several rings, a connecting rod and a pin. The total volume of the engine cylinders consists of the working one, as well as the volume (this path will be conditionally V) of the cylinders. The ratio of the total displacement of a motorcycle engine to V cylinders is called the compression ratio. The higher the compression ratio, the more efficient the engine will operate. In modern engines, the compression ratio can reach 9-10 units. And sports engines can have better characteristics - from 12 and above. It must be said that the design of two-stroke and four-stroke engines is slightly different. Let's look at the differences between them now.

Aprilia RSV4 RR, RSV4 RF (model 2016) - 198.5 hp. at 13,000 thousand rpm

Second place in the ranking. The compiled list clearly shows how difficult it is for motorcycle manufacturers today to cross the threshold of 200 hp. What a difficult task this is.

More recently, the Aprilia model had a “modest” 181 hp engine, but the latest tweaks for the 2016 model year motorcycle have made a serious improvement in it. The result is obvious - 198.5 hp, the most powerful production liter bike currently sold in America.

It’s surprising but true why so few people buy such a technological masterpiece.(?)

Four stroke engine

In motors of this design, the cycle is four power strokes. What is the essence of his work? In one cycle, the crankshaft makes two revolutions. During the intake phase, the crankshaft goes to bottom dead center, and the fuel mixture enters the cylinder under the influence of vacuum. Next comes the compression stroke. What is happening at this moment? The piston rises and compresses the working mixture. At this time, the intake and exhaust valves are closed and the fuel is ignited by a spark plug. When fuel burns, gases expand significantly and produce useful work. Next, the piston, when moving upward, squeezes the gases through the exhaust valve.

Can you trust the odometer?

On most old classic motorcycles, the odometer is mechanical and its readings, with some skill, can be adjusted to any value. With electronic devices (including on-board computers of modern foreign cars), the same operations can be carried out if you have the appropriate software. The odometers themselves are interchangeable within the same model, and in the case of “China” – even between different manufacturers.

The previous owner of the bike could have distorted the indicators unconsciously, without malicious intent. By replacing the gear ratio in the gearbox, the driven sprocket, the wheel, or simply by installing tires that are not the standard size. Depending on where the speedometer (odometer) takes data, it may show not actual, but estimated mileage. Sometimes the device may simply be broken, and who knows how many kilometers the bike has traveled since then?

V-shaped two-cylinder unit

This unit is one of the most ancient. But today this scheme is still alive and in use. This design with two cylinders, a common crankpin and a V-shape design has no problems with the oscillating couple effect. The best cylinder camber angle is considered to be 90 degrees. Vibrations from this unit during operation are negligible.

This is an almost perfect motorcycle engine, but the camber angle makes the dimensions larger, making it difficult to mount it in the frame. But it is possible to do this - this is confirmed by motorcycles from Ducati. This arrangement is unconventional, but it is still found on sports cars participating in world championships.

What exactly does “high mileage” mean to you?

Final question: what costs are you willing to spend for a good motorcycle? Stop buying new tires? Or will you go further - overhaul the engine, rebuild the suspension, repaint everything down to the screw? In terms of used motorcycles, “hitting the jackpot” is becoming more and more difficult, and for the vast majority of devices the ratio of purchase price to maintenance and repair costs is always more towards the latter. If you choose a cheap, lightweight two-stroke bike, you will repair it often, regularly, but little by little, and if you buy a “liter” tourer with dropsy, you will avoid repairs for a long time, but if it happens, you will have to fork out quite a bit.

The mileage completely loses its relevance if you are offered a completely complete legendary motorcycle. Like the Old Lady Java, Lend-Lease Harley WLA, or BMW R35 - for which the very fact of serviceable existence is already a feat, and a large number on the odometer is a natural sign of venerable age. Even if you are not a fan of oldtimers - tell me frankly - in what order should you look at the odometer when considering a “cult” model, or a copy of a bike that once touched you to the core? A truly “own” motorcycle is chosen with your heart, not your wallet. I'm sure a true motorcycle fan will agree with me.

Two stroke motor

In motorcycle engines of this design, the working cycle is completed in one revolution of the crankshaft. Another feature is the absence of an inlet and outlet valve in the design. Their function is assigned to the pistons. The latter, when moving, open and close channels for supplying the fuel mixture and releasing exhaust gases. On some models, a reed valve may be installed on the inlet. Under the piston in two-stroke engines there is a crankcase, which also participates in the gas exchange process.

When the piston moves to top dead center, the fuel mixture enters the combustion chamber in the sub-piston space. Gases remaining from the previous cycle are released through the space above the piston. When the windows close, the compression stroke begins. At top dead center, the mixture is ignited by a spark. Gases are then formed during combustion, they expand and push the pistons down. When the latter drop two-thirds of the stroke, a window into the exhaust system will open. A new portion of the working mixture will flow through other windows. And when lowering, the piston will create the necessary pressure. This process is called purging, and the channels are called purging. Modern engines have a large number of channels. This is the so-called return-loop blowing.

2-stroke / 4-stroke

The two main types of motorcycle engines are two-stroke as well as four-stroke power sources.

Two-stroke bicycles can usually be identified by their special exhaust systems, which are usually referred to simply as "two-stroke pipes" or "two-stroke growth chambers". Push-pull pipes are pretty darn easy to find, with spherical developing chambers usually topped with tiny mufflers.

The vast majority of motorcycles produced today are of the four-stroke (with the main exception being motorcycles). 4-stroke bike engines are cleaner, more reliable, last much longer, and require unnecessary maintenance than 2-stroke engines. They are also very economical and do not consume oil.

Two-stroke in-line two-cylinder internal combustion engines

Almost all motors operating on this principle operate according to the same scheme. It uses a crankshaft, and the connecting rod journals on it are located at angles of 180 degrees. These models have fewer disadvantages than their four-stroke counterparts. This can be attributed to the fact that the spark in each cylinder jumps after a full revolution of the crankshaft. As a result, there is no uneven flash, which is found in four-stroke engines.

But the effect of the so-called swinging pair is great. At high crankshaft speeds, this effect can manifest itself in obsessive vibrations. The problem is further complicated by the fact that these two-cylinder engines require separate chambers. This means the design has a central main bearing, as well as oil seals. As a result, the crankshaft will be wider than in its four-stroke counterpart.

BMW S1000RR - 190.4 hp at 12.500 thousand rpm

Just recently, the previous HP4 model (derived from the S1000RR) could only be content with the last place in the table. The new basic road version of 2015 has caught up, its capabilities have increased today, to the same 190 hp. It is noteworthy that the year before last, sportbikes with similar engine power could only count on sixth place in the ranking. What we mean is how quickly the technology of new generations of internal combustion engines is moving forward.

Two-stroke V-twin engine

An engine built according to this design is now a rarity. One example of such a unit is the NS 250 from Honda.

It was created primarily for the Japanese market. Since the motor is two-stroke, a separate crank chamber is required, which is structurally impossible to do. The “swinging couple” cannot be avoided, but the forces that are characteristic of two-stroke engines do not apply here.

There are never too many repairs?

How to determine the resource if, against the backdrop of a solid mileage, there is an abundance of clearly “fresh” (or foreign) spare parts in the motorcycle? On the one hand, this is an understandable matter, especially if we are talking about old models, such as domestic “opposite” cars, stock spare parts for which have not been produced for a couple of decades. Nowadays, it is almost impossible to find a completely complete, serviceable, not repainted (at least partially) old Ural Stroller in the factory version. On the other hand, the bike can be not just well-groomed and in good working order, but extremely tuned, technically – not at all the same as it came off the assembly line. Frequent repairs and active tuning can either help or harm a motorcycle, worsening handling or power characteristics. An unsuccessful “experiment” may be “dead” already within the first hundred.

By and large, an old motorcycle that was regularly ridden, which was honestly maintained and diligently updated, will be in better condition than a newer machine with less mileage, on which nothing was changed, but was serviced “from time to time.” If you find it difficult to assess the “condition-mileage” ratio on your own, submit the equipment to an independent expert judge (fortunately, there are now plenty of places where diagnostics can be carried out).

In-line three-cylinder engine

This transversely mounted unit is a development of the in-line two-cylinder engine. Engineers tried to find compromises between vibration and the size of the four-cylinder internal combustion engine. This scheme was the main one in the 70s.

There are many examples of this. Basically, Japanese Suzuki and Kawasaki equipment was used with in-line three-cylinder engines. There are other motor design schemes. These are four-cylinder, six-cylinder in-line and V-shaped units.

Single cylinder

• Armstrong MT500
• BMW R2
• BMW R25
• BMW R26
• BMW R27
• BMW F650CS
• BSA Blue Star
• BSA C15
• BSA B44 Shooting Star
• Cagiva 350 SST
• DKW RT 125
• Ducati Mach 1
• Ducati Supermono
• Harley-Davidson Topper
• Harley-Davidson Baja 100
• Harley-Davidson MT350E
• Honda CB125
• Honda CBR250R/CBR300R
• Honda CRF series
• Honda Dream Yuga
• Honda Thunder
• Honda NF110i/125i
• Honda Rebel 300 (single cylinder, after model change in 2020)
• Honda Super Cub
• Honda Winner
• Honda XBR500
• Honda XL250
• Honda XL350R
• Husqvarna Vitpilen / Svartpilen 401
• Husqvarna Vitpilen / Svartpilen 701
• Honda XR250
• Kawasaki Z125 Pro
• Kawasaki KLR650
• Kawasaki Ninja 250SL
• KTM 200 Duke
• KTM 390 Duke
• KTM 690 Duke
• Langer's single "NSU Bison 2000" 2 liters
• Moto Guzzi Cardellino
• MV Agusta 125 SOHC
• MZ SM 125
• New Werner
• Norton CS1
• Peugeot Jetforce
• Royal Enfield Bullet
• Royal Enfield Himalayan
• Sachs MadAss
• Suzuki Boulevard S40
• Suzuki DR-Z400
• Suzuki DR650
• Suzuki Gixxer 150, 250, SF250
• Suzuki LS650 Savage
• Suzuki TU250
• Triumph Ricardo
• Tiger Cub Triumph
• Yamaha MT-03
• Yamaha SR400, SR500
• Yamaha T-150
• Yamaha XT225, XT250 (Serow)
• Yamaha XT 500, XT 600 (Ténéré)
• Hyosung GD250N
• Werner Dienstkrad 1440 cc single cylinder steampunk motorcycle. Cm
• Wilkinson T.M.C.

Device

The placement of the cylinders here is opposed (the same as on other Soviet motorcycles in the heavy class). In terms of design features and technical characteristics, this is a domestic forced internal combustion engine for road-type motorcycles.

Cylinders located horizontally are cooled much better, and the crank mechanism is better balanced. As for the power system, the engineers provided a separate carburetor for each cylinder. This made starting easier and increased the power of the motorcycle engine.

Unit index – MT8. In addition to design differences, it was superior to other engines in technical characteristics. So, the power is 32-35 horsepower. The maximum speed was 90-105 kilometers per hour if the motorcycle was equipped with a sidecar. Fuel consumption was six liters per 100 kilometers. At the same time, the engine capacity of the motorcycle is only 650 cubic centimeters.

Supply system

Gasoline with an octane number of at least 93 is used as fuel for carburetor motorcycles.

Motorcycle engines have a power supply system that includes a fuel tank, valve, filter, air filter and carburetor. Gasoline is located in a tank, which in most cases is installed above the engine in order to flow by gravity into the carburetor. In other cases, it can be supplied using a special pump or vacuum drive. The latter can be found on two-stroke bikes.

The fuel tank has a cap with a special hole where air enters. In many foreign motorcycles, however, air enters through carbon tanks. And some have a lock on the lid.

The fuel valve prevents fuel leakage.

Air enters the carburetor through the air filter. The filter comes in three types.

1. In the compact oil type, air enters the center, turns 180 degrees and passes into the filter. At the same time, it is cleaned when the flow turns, where heavy particles settle in the oil. The engine of the Ural and Izh motorcycles is equipped with such a filter. However, other types, paper and foam, are used abroad.
2. Paper filters are disposable. They must be changed at every maintenance.
3. Foam filters are reusable - they can be washed and re-soaked with oil.

Sports motorcycles with engines of 250 cc and above today have a so-called “direct intake” system, where air is taken in from the front of the fairing, thereby increasing the filling of the cylinders at high speeds.

Design advantages

The main difference between this engine and all others is the combustion chambers of a more advanced design. They have a cast iron sleeve, which is enclosed in an aluminum alloy cooling jacket. There are no longer cast iron cylinders, which were constantly subject to overheating on Urals and other heavy motorcycles.

This approach made it possible to significantly improve cooling and completely eliminate the operation of the internal combustion engine in overheating mode. At the Urals they came to such a design only in the early 80s. Another feature is a monolithic, rather than composite, crankshaft, as well as liners in the lower heads on the connecting rods (rather than rolling bearings). This made it possible to significantly reduce noise. Owners also have the opportunity to easily repair the motorcycle engine (in particular, the crankshaft). Moreover, such repairs can be performed up to four times. It was believed that this unit often jammed due to these same liners. In fact, the engine jammed not because of this, but because of the negligence of the owners. The oil was not changed in a timely manner; low-quality oils were used in the motorcycle engine. The only drawback of this power unit is the imperfect oil filtration process using a centrifuge. Otherwise the technology was good and very modern.

Yamaha V-Max - 197.4 hp at 9,000 thousand rpm

Another motorcycle legend, the V-Max model. Despite its very strange roots in the intricacies of which obvious signs of incest are visible, this model of a sportbike shows quite good results time after time. Its huge 1.679 cc engine easily produces 197.4 hp. at 9,000 thousand rpm. The Americans received such indicators during their measurement tests. In terms of torque, this 1.6 liter engine was head and shoulders above all other competitors.

The only negative about this V-Max model, which is logical, is that it is excessively heavy.

IZh engines

Created in 1987 at the Izhevsk plant, the IZH motorcycle is still popular among motorcycle enthusiasts. And there is something to love about it - it is a reliable and high-quality motorcycle. It has a strict classic design and a number of advantages over “Jupiter”. However, there is also a minus - the crankshaft of the IZH motorcycle engine is much larger and more massive. What does this affect? Due to this, the engine operates at lower speeds, resulting in reduced power. This is a two-stroke single-cylinder engine. It is filled with a mixture of oil and gasoline.

With a power of 22 horsepower, the motorcycle engine capacity is 346 cubic centimeters. This is a good indicator for such a small volume. If you use the unit to the maximum, you can reach a speed of 120 kilometers per hour.

Units

Another common unit of measurement for power is horsepower.

Relationships between power units

Chinese engines

Nowadays, not everyone can afford to restore domestic motorcycles or purchase high-quality Japanese or American motorcycles. Chinese products are much cheaper and are in good demand. There are no engines that would have been developed by Chinese engineers. All units are recycled internal combustion engines from Honda, Yamaha, Suzuki or sold licensed units from the same brands. Four-stroke copies are of quite high quality, as they are manufactured on Japanese lines. But many people have purely negative opinions regarding two-stroke internal combustion engines.

Motors from China have two markings. One is used for internal use, and the second is needed for the rest of the world. The first letters in the name are the plant. The number 1 means that the engine has one cylinder, 2 means that it has two. The third letter is volume. So, I is a 125 cm3 motorcycle engine. A, B - 50 cm3, G - up to 100 cm3. L – up to 200 cubic centimeters.

Owners of Chinese licensed engines claim that in terms of quality and technical characteristics, as well as reliability, they are much better than domestic power units. They are also practically problem-free - you need to understand that this is not Chinese folk art, but a motor manufactured under license. Even a 250cc Chinese motorcycle engine will have a sufficient level of reliability.

BALTMOTORS MARINE DAME 265/280

* The indicated price is not a public offer and is subject to change. Current price and availability - check by phone or directly at the point of sale.

DESCRIPTION

A stable rowing boat for fishermen with the ability to install a motor of up to 5 horsepower. The standard package includes two aluminum dismountable oars, 2 seats, a pump, a set of tools, a motor mount, and a transport bag. The boats are made of durable PVC with a density of 1100 g/m2 and a thickness of 0.9 mm. The bottom is a grid made of moisture-resistant plywood. It is possible to install an inflatable Air Deck for an additional fee.

Inflatable boats are a simple, inexpensive and reliable means of navigation.

• mobility;
• comfort and safety;
• compactness - can be stored in a dry room without purchasing a separate garage or place on the pier;
• profitability - prices are significantly lower than for aluminum products;
• a light weight.

Using technological experience and selecting the best suppliers on the market, Baltmotors offers high-quality Deima boats that can be equipped with Baltmotors Marine motors.

PECULIARITIES

Honda F6C.

The original one and a half liter Honda F6C “Valkyrie” is not included in our selection today, but its new version, released in 2014, can be considered when choosing a cruiser that goes beyond the usual idea of ​​clumsy motorcycles of this type. When creating this motorcycle there was not a single attempt to copy Harley. The Honda F6C is a decidedly new take on the cruiser concept. This is technically a Golda with the plastic, panniers and touring bells and whistles removed. This probably allows the six-cylinder engine to shine a lot more. On the other hand, the motorcycle has lost Golda's practicality.

Honda Rune.

If you are an extremely modest person, you should probably avoid buying Runes. You will definitely try to buy one of these, even if you are brave enough to be seen wearing it. The Limited Edition is built on the same 1,832 cc six-cylinder as later Golds, but the wrapper is completely different: an all-new chassis and an innovatively modern take on the classic cruiser look. Never officially sold outside of America.

Honda F6B.

Perhaps the F6B is a good compromise between the fat Goldwing and the cruiser F6C. Trying to be on the wave of fashion for baggers, the F6B loses the top case and the backrest of the second number, the height of the windshield is reduced, and the ground clearance is lowered. The straight-six still lies underneath, and the F6B might be the best way to experience this engine on a bike that still has plenty of touring ability but can also be ridden in style.