This is exactly the problem. You must check the connections between the loom connector and reg/ rectifier where they clip together. You can seaqrch this forum for the problems that others have encountered but your description of the problem is the classic 'has not been assembled' properly. I know because my bike was the first to have this problem. The pins at this connector are very small and you will find that the earthing pin might well be balckened. If it has not deteriorated too much you should be able to clean it up and then fill the connector with vaseline or grease and clip back together firmly. You should hear an audible 'click'
If the problem has been there for a while the terminals might have heated up and distorted the connector making it unreliable to make a good connection, this is where your Warrenty will come into play as some have had thier entire loom replaced. Yamaha are aware of this problem and you among many that have had this situation. All because of bad assembly.

Hope this helps. Have a look at other threads on this subject and tell your mechanis to turn his attention to the connector.

Hope you get it sorted soon.

SteveD

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