| The motrax one is easily sorted if you bend it outwards slightly and space the plate off it with an extra nylon nut between plate and bracket and make sure the single allen bolt is tight. The reason it comes off is that the wheel catches it under full compression, its worse with lower rear ride heights/incorrect rear spring. If you are knocking plates off I'd be looking at raising the whole bike up or one day you may take the sump off! | 
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