gilera 172 engine vibrates at around 60-70mph

i was riding my bike erlier arfter rebuilding the engine (new crank, bearings and seals) and i noticed that it is smooth untill i get to around 60ish then all of a sudden the engine starts to vibrate quite badly ive never had this on any of my other bikes does anyone have any ideas what it could be thanks.

 

its not the engine vibrating in the mounts it feel like its coming from inside the engine.

 

my gilera runner does that but i just think its going for it :yahoo:

 

Well the whole bike doesnt shake but the footboard does and it screams abit for a 4 stroke

 

ye thats what mine does spoke to psn today they said its my bike over revving because the standerd gearing can only really go to 62mph so could do with a gear up kit. what a shame another excuse to make my bike go faster lol

 

Thats kinda worrying considering mine does that at about 20-25 mph :O

 

oh dear that dont sound good