Sounds like it could be a serious Voltage drop when you crank the engine. Before taking it to a dealer, I would check the condition of the battery terminals, as well as the starter terminal. It might pay to check the condition of your 'new' battery as well. Also, have you checked the condition of your brown connector(s)?
If you have a brown connector issue, your battery won't be getting charged properly, and will run itself down.:thumbup
Dave
Hi Guys, fiitted the new starter relay, problem over, unfortunately I had already ordered an Aprilia one on E bay before reading about the Yamaha one, still at least I will know next time, Now to look at the brown connector issue. Anyway thanks for the help guys.