After the strip down I have decided to concentrate on the chassis first and once this is complete move on to the engine, so the only place to start is the main frame. As some of you will know these are not anodised like the road bikes so are subject to corrosion. Nothing to serious on this one just lots of small areas of pitting.
20181015_114956 by Paul Goat, on Flickr
20181015_115015 by Paul Goat, on Flickr
The only way to really get rid of this is by manual labour
I used wet and dry, scotchbrite, phosphoric acid and elbow grease, elbow grease and even more elbow grease 
I was quite happy with the result though, my personal preference is for a satin scotchbrite finish, really not a big fan of polished aluminium myself but each to their own
20181019_154633 by Paul Goat, on Flickr
20181019_154641 by Paul Goat, on Flickr