07-03-17, 10:20 AM
If the onset of the noise was sudden that does not suggest camchain to me. They tend to gradually get noisier and then go quiet again once there's enough slack in it for the adjuster to click to the next step.
It may be a blocked jet in one of the carbs causing one cylinder to run lean, hence you're getting a bit of pre-ignition when you open the throttle.