"Genesis" is Yamaha's marketing name for a range of innovative high performance

multi-valve In automotive engineering a multi-valve or multivalve engine is one where each cylinder has more than two valves. A multi-valve engine has better breathing and may be able to operate at higher revolutions per minute (RPM) than a two-valve engine ...

motorcycle engine A motorcycle engine is an engine that powers a motorcycle. Motorcycle engines are typically two-stroke or four-stroke internal combustion engines, but other engine types, such as Wankels and electric motors, have been used. Although some moped ...

s.Feature: The Versatility of Yamaha 4-Strokes - The Character of Yamaha Engines
/ref> The flexible design of the engine allowed Yamaha to use it on a variety of configurations, from sport bikes to outboard engines.

The five-valve engine

Cutaway of motorcycle inline-four engine1

The

DOHC An overhead camshaft (OHC) engine is a piston engine where the camshaft is located in the cylinder head above the combustion chamber. This contrasts with earlier overhead valve engines (OHV), where the camshaft is located below the combustion cha ...

Genesis engine has five valves per cylinder and

downdraft In meteorology, an updraft is a small-scale current of rising air, often within a cloud. Overview Localized regions of warm or cool air will exhibit vertical movement. A mass of warm air will typically be less dense than the surrounding region, ...

carburetors. Yamaha adopted the 5-valve concept, using three intake valves and two exhaust valves per cylinder, because it allowed both excellent

volumetric efficiency Volumetric efficiency (VE) in internal combustion engine engineering is defined as the ratio of the mass density of the air-fuel mixture drawn into the cylinder at atmospheric pressure (during the intake stroke) to the mass density of the same volu ...

and high rpm. As designers began to appreciate the benefits of multi-valve layout, 4-valves-per-cylinder (and even 3-valves) became common. In a multivalve engine, maximum rpm is limited by the size of the largest valves: in a 3-valver, the exhaust valve is larger, and in a 4-valver, the inlet valves are larger. The significance of the five-valve engine compared to other multivalve configurations engines is that (like a 3-valver) there were more intake valves than exhaust ones; yet all valves were small and of very similar sizes and weights. Downdraft carburetors were adopted for improved gas flow, but, for motorcycles, a perceived disadvantage was that the intake

airbox An airbox is an empty chamber on the inlet of most combustion engines. It collects air from outside and feeds it to the intake hoses of each cylinder. Older engines drew air directly from the surroundings into each individual carburetor. Modern ...

was above the engine, taking up space from the fuel tank, rather than being sited conventionally behind the engine. However this apparent disadvantage was an advantage as it allowed for pressurisation of the airbox. Also Yamaha dealt with this apparent loss of fuel tank volume by building the tank lower and using an electric fuel pump to pump fuel to the bank of carburettors above. A deeper fuel tank also gave a small advantage as it centralised weight and moved CoG lower. What could be argued is that the Genesis concept (not just the inclination of the engine, although on the FZ750 was a radical 45 degrees, on the FZR1000 a less radical 35 degrees, a feature now generally universally used in the modern (post 1990 sportsbike thus allowing downdraft air induction and airbox pressurisation, but also the use of beam frames as opposed to spine or perimeter frames previously commonly used) set the architecture for the modern sport bike.

Applications

The Genesis engine first appeared on the 1984

Yamaha FZ750 The Yamaha FZ750 is a sports motorcycle produced by Yamaha Motor Corporation between 1985 and 1991. The FZ750 is notable for several reasons, perhaps the most radical being the 5-valve cylinder head with a radial arrangement. This became somethin ...

and was later used on a variety of motorcycles for different kinds of markets. The design was used for parallel-twins (such as the

TDM TDM may refer to: * ''TDM (film), TDM'', a 2023 Indian Marathi language, Marathi comedy film * TDM (Macau) (), a Macanese radio and television network * The Yamaha TDM, a motorcycle model * Target Disk Mode, a boot mode on certain Macintosh compute ...

and the TRX) as well as for four-cylinder models. Both fours and twins had the cylinder block slanted forwards 45 degrees. The Genesis engine was also used in the

Yamaha YZF-R1 The Yamaha YZF-R1, or simply R1, is a -class sports motorcycle made by Yamaha. It was first released in 1998, undergoing significant updates in 2000, 2002, 2004, 2006, 2007, 2009, 2015, 2018

, FZX700, FZ750, and the USA-only FZ700. Other applications ranged from the Supersport YZF-R6 and YZF-R1 models using electronic fuel injection with YCCT and YCCI to the less extreme but still powerful Yamaha FZ6 (4 valve per cylinder) and FZ1 Fazer line which had a simpler fuel injection designs but was essentially the same basic engine design. The most significant changes made were the 4-valve per cylinder configuration and the crossplane crankshaft found on the YZF-R1 2009, along with the change of cylinder sleeves to steel for high precision and high temperature durability. Throughout its long period of production, the Genesis range has successfully provided performance and reliability. Because of its high performance capacity (usually from 100 BHP - 350 BHP), the engine has also been employed in various other uses such as gyroplanes and high power marine engines, making it an affordable solution for a high performance applications. The engine is also used in a racecar championship in Norway calle
SevenRacing.
It is a copy of Lotus Super Seven, and is produced by MK and Stuart Taylor.

References

{{DEFAULTSORT:Yamaha Genesis Engine Motorcycle engines Genesis engine