Re: What type of grease??
Red moly synthetic grease such as Mobil 1, Lucas, Redline CV2, or others will last a very long time and make non sealed bearing much more suited to the high speed running of a motorized bicycle because it will run cooler and stay on the races better. Really pack it in there good to avoid air pockets.
KTM50 Schwinn Chopper - 6000W E-Motard - 52cc Auger BMX - 9sp+CVT 52cc Cagllari Moped