What are the different motorcycle engine configurations?

Answer 1

Here are the most common engine configurations as summarized in Timberwoof's Motorcycle FAQ.

• Single: Called a �thumper.� Most dirt bikes, many small motorcycles, and the following BMW models: F650, R20, R23, R24, R25, R25/2, R25/3, R26, R27, R35.

• Inline Twin: two pistons side by side.

• V-twin: Harley Davidsons, Ducatis, Honda Hawk and Superhawk, Moto Guzzi, and a couple of Suzukis including the wonderful SV650. The 90-degree twin is very well balanced; other angles may or may not be, depending on whether the crankshaft has one pin or two.

• Flat-twin: classic BMW design offers good balance and natural air-cooling. Also called a "Boxer" or opposed-twin engine, the firing of one cylinder helps cancel vibrations from the firing of the other cylinder. Also used by Harley-Davidson in the XA motorcycle copied from BMW during World War 2. See also the Ural - a Russian motorcycle reverse engineered from wartime BMWs. See also the Japanese Marusho motorcycle, yet another BMW copy.

• Inline-three: Three pistons in a line. Typical examples are Triumph and BMW K75. Historically seen in Kawasaki 2-stroke form in the 1970s

• Inline-four: Staple of the UJM or "Universal Japanese Motorcycle," found in everything from the 400cc Honda CB-1 to the 1200CC BMW K1200. In the UJM it's mounted with the crankshaft sideways; in the BMW K it's mounted with the crankshaft aimed north-south and the pistons off to the left. Imperfectly balanced, with the potential to be objectionably "buzzy" in the absence of balance shafts or vibe-damping motor mounts.

• V-four: Honda VFR 800 (sideways) and ST1300 (longitudinal): smooth like a four and balanced like a twin.

• Flat-six: Honda Gold Wing and Valkyrie: smooth torque monster with low center of gravity. Possesses perfect natural balance without the use of balance shafts or vibration damping engine mounts.

• Inline-six: An awkward engine to package efficiently, but with the same perfect balance inherent to a flat 6. See the Honda CBX1000, Kawasaki KZ1300, and Benelli 750 and 900 Sei.

• Square four: As in the Arial Square four. Four vertical cylinders arranged with the center axis of each cylinder at each point of an imaginary square as viewed from above, looking straight down. A mechanically complex arrangement that is difficult to cool with ram air.

• V-eight: Rare. Currently only used in Boss Hoss motorcycles - usually a General Motors engine. Used in a record-setting Moto Guzzi in the mid 1950s, also occasionally seen in a custom bike, by mating two inline-4s.

In addition to the comprehensive answer above, additional flat twins (boxers) were made by the Chinese, the Russians ( BMW copies) as well as Zundapp, and one by the Japanese. Thumpers come in varying configurations- depending on the angle of the cylinder which can be nearly flat as with Aermacchi 350 and Moto Guzzi Falcone, and at an angle of around 45 degrees in Panther and BSA Sloper. Of course most other single cylinder 4-strokes vary from upright to a few degrees off vertical, such as the approx. 24 degrees of the Vincent Comet. Two-strokes have come in some weird configurations, Honda made a V3 for a few years (two cylinders nearly flat in front, one nearly vertical, like a Ducati, with three carburettors in the "V"). Also, some "inline twins" (more commonly known as parallel twins) have the cylinders "fore and aft" i.e. longitudinal, like the Sunbeam.