Exhaust gas recirculation

[Trailbikeryder]

Hi,

I closed the Exhaust gas recirculation coming out of the cylinder and closed the spot where the exhaust gas goes back into the carburettor. Everything fine. Engine started right up... but, there were "clack clack clack" noises as if the valves needed adjustment. So I put everything back the way it was. Started up, engine came on normal. The clack clack noises were gone.

Question: why would closing the Exhaust gas recirculation cause the engine to do clack clack noises?

I wanted to try this to see if there would be any gain in power. Since the engine was making these noises though, I didn't go for a test ride.