I was helping my cousin with a motorcycle teardown a while back (planning for a café racer build) and was puzzled by something on his '07 Karizma.


The red arrow in the picture above points to a hollow plastic container with a single opening that twists into a hole on the air intake piping.

I'm puzzled as to why Hero Honda went to the trouble of attaching this extra component to the motorcycle. It looks like the effective volume of the intake is increased as a result of this component.

Does it have any impact on the motorcycle's performance ? My hunch is it has something to do with increasing the effective pressure at the engine inlet but can't be sure.

  • Vehicles usually have this type of thing on the air intake for two reasons: 1) to stabilize the air as it is going into the air intake; 2) reduce the noise from the sucking sound of the intake. This is true on cars, not sure on bikes. Reason #1 is to help with performance. #2 is purely for driver/rider comfort. Commented Jun 12, 2015 at 14:18

1 Answer 1


It looks like that piece is before the carb on that bike. It acts as a resonator, helping to damping out noises from the intake without adding restriction.

Plenty of cars have the same thing in the intake. Some cars have a similar device in the exhaust after the muffler. It is often just a short piece of pipe welded into the main exhaust pipe.

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