BF40 Knocking sound high rpm

[fishfeeder]

I recently bought a used Honda

I recently bought a used Honda BF40. It works pretty good but at full throttle there is a knocking sound. If I back off the throttle 1/4 then it goes away. Any ideas on what this could be?

 

[cheeysbear]

Got new plugs in it?

Got new plugs in it?

 

[fishfeeder]

"Yes, when I bought the engine

"Yes, when I bought the engine I changed the oil, lower end oil and the spark plugs."

 

[pailolo]

Is the fuel fresh?

Is the fuel fresh?