vibrates

Hey guys I did the whole 6.5hp harbor freight engine upgrade on the the green doodlebug mini bike... After riding it I noticed that when we ride it it vidratessooo much. Any reason why you think? Thanks in advance! Martin

I'm still kinda new here so if there was a thread on this subject, I've missed it. Kindly refer me to said thread on engine vibs...lol I have a "new" predator 212, modified and up and running. I don't think I have a problem with it. However, I'd like to discuss the engine vibration issue...