Ever since I have had my 650 it has had a rattle / buzz at about 70 mph ish. I have always thought it was coming from the plastic cheek pieces around the radiator, as when I first had the bike I removed the radiator to do a valve check and found that the rubber pieces on the four tabs that locate the inner cheek pieces to the radiator were all missing. I replaced them with some appropriate heat shrink, but it's always been a bit of a loose fit.
Today while checking out the gear linkage and topping up the oil, I thought I'd have a proper look.
Long story short, the inner cheeks are held in place with three screws. I removed the screws, wire brushed and re-blacked them. On one side I found one of the correct rubber pieces laying inside the cheek piece, so that was installed on the lower tab and the inner cheek reinstalled. Bingo! No movement at all. On the other side, no such luck with the correct rubber, but a bit of bicycle inner tube did an OK job of mostly filling the opening, so just a little bit of movement.
Next time out I will head for a (dreaded) motorway and see if the rattle had gone, I suspect it will have.
