I think you should have got a different battery one like the stock one or similar. That one that you bought is kind of too small and will bounce around in the battery box too much as well. I am a motorcycle mechanic as well I have seen people try and substitute stuff like that before it ends up being more trouble than it is worth. If you can return that Battery and get a good Gel battery or one of the new lithium ion batteries that are available for the bike now I have a 2009 YFZ 450R and could have got one for my bike. If you modify that bracket as well if may cause more problems with holding everything in there that stuff gets vibrating around in there a lot more than you think sometimes.