jd666

it isnt exactly a technical term. more of slang rather than anything else. and there isnt much more to explain.

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- KTM Duke 200
- Yamaha RXZ 5 speed

sudharma

You want to know more about the Thumpers?
Visit The Thumper Page

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ashes

arrre guys....i simply want to know WHY DO THEY THUMP??

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Grease Monk

Thumpers are defined as high capacity single cylinder motorcycles. Both of these traits give it its characteristic sound.

The primary source of sound in a thumper is its exhaust note, so all points below revolve around exhaust.

1. Low pitch (also explains why exhaust note doesnt seem as continuous as non-thumpers)

a. Single Cylinder: Since only one cylinder is performing all 4 strokes of the engine cycle, the exhaust gases escape only once every 4 strokes of the piston or two revolutions of the crank. When compared to a twin cylinder engine which will have 2 exhaust strokes with in the same time at the same rpm. Frequency is inversely proportional to time, so the longer it takes between the two sources of sound, the lower the perceived pitch.

b. High Capacity: The fact that a thumper has to compress a greater volume of air fuel mixture at once during a compression stroke than a low capacity single cylinder or an equal capacity twin means that it faces more resistance, leading to a slower running engine. This slower running engine means less rpms and hence less exhaust strokes per minute leading to a lower pitch exhaust.

2. Volume (of sound) (also kind of explains boom-iness):

a. High Capacity: Since the engine has to exhaust a larger amount of exhaust gas from the engine in a relatively short amount of time, exhaust gases tend to exit with greater speed. THis is perceived as a louder tone than the exhaust from a lower capacity engine (im not sure if this is right, someone please verify).

ashes

^^^thanx man!!

now i know

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