My XJ makes a tapping noise. What causes that?

[radare]

My XJ makes a tapping noise. What causes that?

Because the XJ600 uses a nearly all-aluminum engine and because the engine is air cooled, internal noises tend to be amplified and propagate throughout the engine. This makes determining the source of noise somewhat difficult.

That being said, there are three main sources of tapping noise for the XJ, in decreasing order of likelihood:

• The oil drivepin rattle (clutch rattle) (this noise will go away or get much quieter when the clutch is pulled in).
• Carburetors out of sync causing balance wave noise during combustion which propagates
• Valve tapping caused by out-of-spec valve clearances (having valves too loose or too tight can both result in noise)
• Timing chain noise caused by a defective or badly worn tensioner

If you've ruled out clutch rattle as the culprit, try fine tuning and syncing the carburetors and also checking valve clearances. If all of these items check out and the bike still makes a tapping noise, it may simply be the normal sound for an XJ600 engine. Here's a video of my bike idling. This is pretty much how every XJ that I've heard sounds:

Cold:
[youtube]w2tN1U0VkCE[/youtube]

Hot:
[youtube]3dPzvpuOr8g[/youtube]