Vinegar cotton wool done! Keep well away from any branded oxide removers (acids) (Aq) solutions sold in halfords etc trouble is they don't just stop at cleaning!
After a closer look tonight it appears the grey coating has long gone on most of the swingarm. You can see on the photo that the grey is still there near the sticker. The streaks are actually where the coating has gone. Maybe somebody has used an acid based cleaner at some point.
1. I'm amazed the sticker is still there. 2. Where is the upper chain slide? Removed for cleaning? Have you checked for chain wear on the underside of the swingarm pivot? The 748/9xx models are prone to this if chain tension is neglected.
Yeah chain guides have been removed for cleaning. What's strange is that the coating has completely gone where the guides were, I would have thought the opposite. You can just see it in the pic. No chain wear to the swingarm.
How very odd! I would get the arm off and send it to be re coated. It won't cost more than 50 quid and your bike will be off the road no more than a week.
Looks like someone has used an aggressive cleaner in the past or salt and age have destroyed the coating. It would be the best option to have it re-coated. Even if fully cleaned it will have no protection from the elements and you will have to clean it very regularly and it's likely to start pitting.
