Lately, I have been hearing a "chik chik" sound from my GD's engine head. The sound is similar to the one produced when drive chain scratches against chain cover. However, this sound is very irregular, i.e. the sound comes randomly while riding it. To my utter dismay, the deaf and dumb Suzuki guys are unable to trace the cause by refusing to hear any sound at all.
I explained to them the sound can be heard only when the bike is running on the road, but they put the bike on double-stand, revved the engine and declared the engine to be trouble-free, adding if an engine develops an anomalous sound then it should be heard by just firing and revving the engine.
The sounds seems to be a result of loosened timing chain scratching with engine components/body. But nothing is conclusive yet. Any ideas what is going on here?
PS: my GD has clocked ~26k and I recently replaced its sprocket-chain set and air filter.