Thank's so much for the welcome guy's, upon inspection of the bike I have come to realise that the previous owner was a moron. I don't think it has had a service for years and I'm surprised it's not seized. It was pretty down on power when I took it apart. The oil was milky and grey, with metal flakes in it. It is a bit disheartening as I don't have the time or money to re-build both the Yamaha motor and my Honda. I have opted to choose the Honda as it's more suited to my size.
I may decide to give this another go in a few months, maybe as a project next winter. It's a shame as I am impressed with the reception I have had here and was looking forward to building myself a little supermoto commuter.
Thanks again guy's. Maybe I will be back in the summer if I persuade myself to buy an R1.