Hi,
I want to change the seal that sits behind the two stroke oil pump and at the same time re-paint the right side casing. I have never removed the casing and am not too sure how to do this.
Obviously remove the kick start but do I need to remove the oil pump also before undoing the main case Allen screws?
Is that all I need to do - is it that easy?

You don't even need to remove the oil pump if you don't want to. Probably better if you do since you want to change the seal on the inside so pump will have to come off. Make sure all the screws are out... some models have a couple that are hard to see...

Does the side cover say "Magnesium" on it? If so, can be hard to paint. Don't be surprised if paint doesn't want to stick. They make special primers for magnesium or you can use Gibbs Brand Lubricant before painting.