before re-shimming have a look to see if when the cams had been tensioned & aligned, that the spring on the cam gear was done propperly.. as that could very well cause a rattly (sp!) top end.
kon[/so how do you retension the cams?
10W40 or 15W50 in the UK climate, really.
And ALWAYS Fully Synthetic.
As for your rattle, Sean, has it started doing it all of a sudden? Or since a rebuild? Or...?
If you've had the camshafts out and replaced them without retensioning the inlet cam gear, then this will be your issue.
Yamaha heads don't really suffer from top end oil loss unless the engine has had an entirely piss poor service record.
Need to really know when it begun doing it to take it any further, dude.
how do you do that kon?
and did someone say they use 5w 30?
thought 5w-40 fully syn was best to use?