I had to put a washer on the inside too on the freewheel side, best idea is to try and video the sound, its not easy if you have only a phone or a action cam, but do try and upload it to youtube, I did with my first motor and YOSE deemed it faulty, whether it was or not remains unclear for several reasons, if you read back on this thread you can gauge the problem I had and how I solved it -
But to sum up, it was like a clutch slipping sound from the motor at high speed mainly under load, there was a click and the motor would loose power for a split second at intermittent times during a ride, mainly at throttle use to move off from a standstill. YOSE kindly sent me two motor internals as the second one had damaged threads and the 3rd seem to work fine, however the third was only tested on my old non-yose stealth controller, when that died I use the YOSE controller and that caused my cut off problem to reoccur, I firmly believe these controllers weren't designed with the 350w motor in mind as mentioned I have the same controller for my YOSE 250w ( not 1 problem running that ) the only other possible idea was my power/battery connector however this was used on my YOSE 250w with no problems. The old non-YOSE stealth controller was mounted inside the battery mount thus not requiring any additional user altered connections from the battery like the YOSE controller requires. I have since purchased another NON-YOSE dolphin battery mount stealth controller and it works perfect, it reduced vibrations immensely and has not cut the motor out once. Above all although YOSE are a solid brand and for anyone on a budget who wishes to attempt an ebike build they are a good company to deal with including the after care service... however bear in mind they are relatively cheap.