TOPIC:

Changed out the plugs and ran some seafoam (hi-potency carb clear additive) on my bike last week and now it runs great, but making audible vibration noise from the left side of the valve cover area. Is this a potential BIG PROBLEM? What could cause this and how can it be fixed?

carb cleaner... oops

where did you run the seafoam?

This noise started after the Seafoam treatment?

Suggest listening around with a stethoscope or stick to narrow down location of noise.

Is it pre-ignition? (run on three to see)
Reed?
???

-Duck

I can't se an additive causing the problem. Could be coincidental that something broke. I would remove valve cover and have a look. Something loose or broken in top end can be a major problem.

ran it in the gas 1/3 bottle to a tank, with new plugs