There is no deny that aHarley - Davidsonmotorcycle has a singular auditory sensation , peculiarly if the silencer have been removed ! Even with themufflerson , however , it voice dissimilar from other motorcycle . The reason for the audio has to do with the way the engine is designed .
If you have translate the HowStuffWorks articleHow Car Engines Work , then you know how a basic four - strokegasolineengine operates . A piston go through the intake , compression , combustion and exhaust system strokes every two revolutions of the crankshaft . When your lawn lawn mower is idling , you’re able to pick up the pop - pop - pappa - pop sound of the individual stroke . What you are actually hear is the speech sound of the compressed gas pedal in the piston chamber escape when the exhaust valve give . Each pop is the sound of theexhaust valve openingone time , and it fall out on every second revolution of the crankshaft .
In atwo - cylinder , horizontally opposed engine , the piston are timed so that one fires on one revolution of the crankshaft and the other fires on the next revolution – so one of the two Walter Piston fires on every gyration of the crankshaft . This seems logical and apply the railway locomotive a balanced opinion . To create this type of locomotive engine , the crankshaft has two freestanding thole for the connecting rods from the piston . The pins are 180 degrees asunder from one another .
A Harley engine hastwo Piston . The remainder in the Harley engine is that the crankshaft has onlyone pin , and both pistons connect to it . This innovation , combined with the V arrangement of the cylinders , have in mind that the Walter Piston can not fire at even intervals . rather of one piston firing every 360 degrees , a Harley engine live like this :
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At idle , you could hear the pop - pop sound followed by a pause . So its sound is pop - pop … dada - pop … pop - pop . That is the alone sound you hear !
