Harley Davidson’s motorcycles have always focused on hard-wearing simplicity, tradition and style over technology and extreme tuning.
Harley-Davidson’s Sportster is a trusted design, having served riders well with its simple, functional configuration since the late 1950s. Harleys have always been very visceral machines. Other bikes may be quieter, more nimble and less affected by vibration, but the sound, feel and even the smell of a Harley is something to be appreciated, not rectified. A Harley with faulty aspiration will be less fuel efficient, it will pollute more and it could lead to the damage of some of the engine components. Worst of all, the Sportster will be robbed of its iconic growl.
1. Start the engine and go for a 15 to 20 minute ride. Make a mental note of when the foreign sounds are most prominent. During start up? At high RPM? In low gears? While cooling down? Noises at all of these stages are symptomatic of different faults. Most noises during cool-down can be ignored, as these are usually just the natural sounds of the hot metal contracting as it cools.
2. Run the engine with the bike standing stationary. Put your ear two to three inches from the exhaust pipe and follow it along its length, listening for a whistling or puffing sound. If you think you can hear one, place your hand close to, but not on, the exhaust. Try to feel a slight blowing or disturbance in the air. Exhaust “blowing” is due to a hole somewhere along the exhaust pipe. Depending on its size and location, it may be able to be resealed with exhaust paste. Failing that, the whole section of pipe will need to be replaced.
3. Listen to the upper part of the engine, by the cylinder heads. An irregular clicking from this location could be loose cams, which will need to be replaced. Alternatively, it could be valve lifter noise; this is perfectly normal. Listen closely to each valve area on the engine. Do they all sound the same, or is one louder than the others? If they sound equal and even, this is a normal operational sound. Loose cams, or lifters will be erratic and irregular in speed and volume.
4. Try moving the bike to an open space where there are fewer objects for sound to reverberate from. In an enclosed space such as a garage or driveway, high frequency sounds can create what are referred to by physicists as “early reflections.” These are like miniature echoes, which, when overlaid on the original sound, can make high-frequency noises sound louder or more prominent. You may find that when listening to your bike in a different environment, the sound mysteriously disappears.