IN­LINE-FOUR

Motorcycle Monthly - - Knowledge -

Lay­out: A bank of four cylin­ders run­ning in-line with each other. Ben­e­fits: Smooth power de­liv­ery and fan­tas­tic peak per­for­mance.

The Amer­i­cans were huge fans of lon­gi­tu­di­nal in­line-four con­fig­u­ra­tions, but it was Flem­ish arms man­u­fac­turer FN that was first to pro­duce an in­line-four in Europe back in 1905. Pre-1920s, a great many com­pa­nies opted to try the stretched en­gine lay­out, in­clud­ing In­dian, Ex­cel­sior, Hen­der­son and Cleve­land.

In the UK, Wilkin­son (the fore­run­ner of Wilkin­son Sword) pro­duced an 850cc model with this con­fig­u­ra­tion called the TMC. The on­set of war saw re­stric­tions kill off pro­duc­tion in 1916.

Vaux­hall dipped into the bike world when it com­mis­sioned the pro­duc­tion of six lux­ury pro­to­type mo­tor­cy­cles in 1922. In the end, only two were built.

When peo­ple re­fer to in­line-fours now, they typ­i­cally mean across the frame fours (trans­versely mounted, not lon­gi­tu­di­nally), such as Honda’s 1969 CB750. But it was the Ital­ian man­u­fac­turer GRB that pro­duced the world’s first trans­verse four in 1923. The GRB tech­nol­ogy even­tu­ally worked its way into Gil­era’s hands years later, via bike pro­ducer Ron­dine, the tech­nol­ogy even­tu­ally go­ing into the firm’s Grand Prix win­ning across-the­frame fours in 1948.

From that time on, trans­verse lay­outs have be­come the main­stream four-cylin­der con­fig­u­ra­tion, ow­ing to their abil­ity to cool all four cylin­ders equally and be­ing able to run shorter wheel­bases than their lon­gi­tu­di­nal sib­lings.

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