Do you hear grinding, knocking, or squealing in the rear wheel when you roll your scooter? Then you need to replace the rear main bearing.
 
This is the real main axle bearing replacement for the GY6 150cc 157QMJ motor only.   We sourced the finest quality precision bearings rated up to 21000rpm.  This bearing installs inside the GY6 gearbox behind the wheel hub and supports the wheel axle.  Measures 20mmx42mmx12mm.  Please measure your existing main axle bearing before purchasing.  
 
May require a bearing press tool to install.  Will require the replacement of other seals and gear oil, not included.