aerox 50 2001

I bought a Yamaha Aerox 3 months ago. I had to brake the engine apart due to having to replace the crank bearings. It put it back together now i am getting a squeaking noise from the flywheel which could possibly be rubbing on the dynimo and whatever is squeaking seems to be slowing the crankshaft down which cuts the engine out. I would be glad of any advice on what this could be or how i could find out the problem. Thank you in advance

Tom G