Editing Straight-twin engine (section)

=== Transverse-engined models ===
[[File:NortonCommandoMKIIA.jpg|thumb|1973 [[Norton Commando|Norton Commando Interstate]] ]]

Many large British motorcycles from 1945 to the 1960s used a straight-twin [[transverse engine]] (i.e. oriented with the crankshaft perpendicular to the frame), such as the [[Triumph Bonneville]] and [[Norton Commando]]. This layout is well suited to air-cooling, since both cylinders receive equal airflow and the exhaust can exit in the well-cooled location at the front of each cylinder.<ref>{{Citation |last1=Coombs |first1=Matthew |last2=Haynes |first2=John |last3=Shoemark |first3=Pete |title=Motorcycle Basics | edition=2nd |publisher=Haynes | year=2002| page=1•31| isbn= 978-1-85960-515-8 | url=https://books.google.com/books?id=D0DhHAAACAAJ}}</ref>

The transverse-engine straight-twin design has been largely replaced by [[V-twin engine]]s; however, the straight-twin design has the advantage of easier packaging of ancillaries (such as the air-filter, carburettor and ignition components), which also improves access to ancillaries for maintenance/repairs.<ref>"Fast Bike" magazine August 1995 page 20</ref> A straight-twin engine using a 270 degree crankshaft can have a similar sound and feel to a V-twin engine with an uneven firing order.
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