So I just got past the break in stage of my 66cc. This is my first post so please bare with me. But at high rpm I get a crazy high frequency metal rattling noise, Almost consistent with the cheap metal fenders vibrating. But I removed those and pinned it down to the left and right of the lower engine. Its pretty loud so I cant judge if its more on one side then the other. It does this with clutch engaged and not, but it will NOT make this noise when pulling up a hill. It runs solid just crazy annoying at higher rpms.