help diagnosing this scary whiring noise

hi there my scooter has just started whiring when its flat out , i can feel it through my ass when its whiring and its getting scary like its just going to blow up or somthing , other thing is when i set off it rides the powerband fine asif it was going to all the way up to 60 then at 30 it drops then revys then drops then revs up to 60 i was looking to see if the rollers were shagged then when i did i noticed the hole where the end of the crank comes through the finned part of the vaiator had gone oval ? culd this be the problem

 

could be,you sure you didnt accidently fit a gear up?

 

nope definitly not dec really sturggling could it be crank/main bearings

 

lololol.
Check the thread on the shaft the variator sits on.

 

yeh its ok but how would this cause this ?