What are the different motorcycle engine configurations?

Answer

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 BMW F650.

• 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 used by Harley-Davidson during World War 2. See also the Ural - a Russian motorcycle reverse engineered from wartime BMWs.
  

• 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.

First answer by ID1369410650. Last edit by Digitalsasquatch. Contributor trust: 16 [recommend contributor]. Question popularity: 144 [recommend question]