Bike: Single Cylinder Bike Engine

A single-cylinder engine is a basic piston engine configuration of an internal combustion engine. It is often seen on motorcycles, auto rickshaws, motor scooters, mopeds, dirt bikes, go-karts, radio-controlled models, and has many uses in portable tools and garden machinery. It has been used in automobiles and tractors.

KTM 690 Duke 3

Characteristics

Single-cylinder engines are simple and compact, and will often deliver the maximum power possible within a given envelope. Cooling is simpler than with multiple cylinders, potentially saving further weight, especially if air cooling can be used.

Single-cylinder engines require more flywheel than multi-cylinder engines, and the rotating mass is relatively large, restricting acceleration and sharp changes of speed. In the basic arrangement they are prone to vibration though in some cases it may be possible to control this with balance shafts.

A variation known as the split-single makes use of two pistons which share a single combustion chamber.

Pros and cons

Single-cylinder engines are simple and economical in construction. The vibration they generate is acceptable in many applications, while less acceptable in others. Counterbalance shafts and counterweights can be fitted but such complexities tend to counter the previously listed advantages.

Components such as the crankshaft of a single-cylinder engine have to be nearly as strong as that in a multi-cylinder engine of the same capacity per cylinder, meaning that some parts are effectively four times heavier than they need to be for the total displacement of the engine. The single-cylinder engine will almost inevitably develop a lower power-to-weight ratio than a multi-cylinder engine of similar technology. This can be a disadvantage in mobile operations, although it is of little significance in others and in most stationary applications.

ENGINE

The latest LC4 showcases twenty-four carats of fun. With this gem of an engine now breathing more freely thanks to the standard Akrapovič slip-on exhaust, the engineers have managed to extract a whopping 75 hp (55kw) from the trademark 690 cm³ single thumper; unseen in the monocylinder motorcycle world. How it happened? They completely reworked the cylinder head, inserted a new, ultra light and extremely strong piston and connection rod, rerouted the air intake through a resonator chamber and provided the improved crankshaft with new sleeve bearings.

As a result, the powerband could also be made a thousand rpm wider, which means an even more uniform power delivery, especially in the mid to high rev range. Twin ignition featuring plug-selective mapping, rock solid but featherweight internals and optimized intake and exhaust systems cultivate this massive mono to be as strong as it is smooth, assisted by an advanced ride-by-wire system which guarantees great refinement as well as low fuel consumption and emission figures. You’re green, while they’re green with envy. And you haven’t even begun mentioning upmarket goodies like a standard slipper clutch.

NEW CYLINDER HEAD

Inside the new cylinder head, roller rockers actuate the exhaust valves while the camshaft powers the intake valves. Therefore, the ignition timings can be controlled with far greater accuracy. The result is more peak power over a broader rev range.

SECOND BALANCER SHAFT

In a free-revving engine like this, you want to smooth things out a bit. That’s why the camshaft serves as a bonus balancer shaft, nipping annoying vibrations in the bud.

A2 ALLOWED

A restricted power version is available for those riders who have just started their two-wheeled career. But restricted power doesn´t necessary means restricted fun: thanks to its lightweight and dynamic chassis, the KTM 690 Duke R is the perfect playmate for all ages. Regardless of your experience level, de 690 Duke is your license to thrill.

ENGINE MANAGEMENT

The electronic engine management system lives to make the LC4 shine. Twin ignition with individual mappings for each spark plug ensures that your precious fuel is always burned to perfection, irrespective of load and engine speed. And then there is genuine ride-by-wire, in other words: electronically controlled throttle valve actuation without any mechanical linkage.