Inside the rear wheeled e-gyro of the Atomik MM450 there is a red spacer. The red spacer is on the axle on left (sprocket) side of wheel that sits between the wheel bearing on the left and the e-gyro motor hub on the right and measures 6mm. Some owners are noticing that with the spacer length as is, it pushes the wheel bearing out of the casing a small amount. Over time, if that bearing continues to stick out it may begin to create slop in the wheel of the bike. Depending on tolerances you may or may not see the bearing sticking out a small amount on your bike. If you dont see this, your done here, have a nice day lol. I have the VMX450 but got the e-gyro kit and when installing the rear wheel as it was fully assembled, that if I held the wheel and pushed on one side where bearing sits, then the other side the bearing would start to push out. So the length of the internals was too wide and wouldnt allow bearings to ever sit fully in the pockets of wheel.
If you do see this and want to take care of it you should look at reducing the red spacer to NO LESS than 5.3mm. Any shorter and you run risk of wheel binding internally. NOTE: TAKE OFF FROM THE LARGE SIDE OF SPACER, NOT THE SMALL SIDE. If you take material off from small side, you will also run chance of wheel binding. Personally I didnt want to flirt with binding my internals so I went 5.4mm, but everyone Ive heard go to 5.3mm has said its a ok. Its a $1.50 part so big deal if you messed up. I didnt have any good machining equipment, just a metal file and digital caliper to measure length. I held the spacer and filed off some material, rotated spacer and filed some more that way I was always flat.
Final tip: Once the wheel is assembled and back together on the bike, consider the use of washers on the axle (just underneath the axle nuts) to take up the clearance and stop the nuts bottoming on the threads before clamping.
BEFORE – SPACER WITH STOCK 6MM LENGTH:
AFTER – REDUCED SPACER WITH 5.3MM LENGTH:
Special thanks to Chris Haertel for finding out the right measurements and also thanks to David (davehour) on rcgroups for the pictures!