Guys I'm after some advice...

The rear sag on my bike (adrenaline 250cc) is 120mm and I think this a bit excessive... Before I go changing the rear shock preload on the bike (will be my usual try it and pray) can anyone offer any advice on the easiest way to do this?

Otherwise it will be a case of pulling off all the panels and all the screws I can find ; )

Cheers
WasNotWas