Yeah monkeying around with geometry and height needs to be done with caution, it will also alter how the bike steers (lower shock, slower and more sluggish steering due to the increased rake). And Ponters did a good job mentioning the car tires and other stuff.
The bloke i bought my bike from had fitted shorter Hagons and the rear tyre had been rubbing through the wires when 2 up ,so i had to stiffen up the springs and replaced them with standard length Hagons ,i only noticed it when the bike was on the Dyno up in the air.
Morris,
That what you found on your tank was the resultant from English Bob rubbing one out on that titty pix of ???
Ya just gotta watch the "Duck of Death" every second!