| Had exactly the same myself. I had fitted a 180 rear and also some track day bodywork. I noticed the rear of the bellypan was very close to the rear tyre compared to the identical kit on Lilys bike. We messed around with the bodywork until we got a decent clearance. On a run out however I took a look at that are of the bike to check if the tyre had contacted the bellypan at all (it had not) but noticed that the section of exhaust you mention was highly polished from the tyre rubbing it. At standstill there was a good few mm clearance but at speed the radius of the tyre increases and hence the contact.
A 180 tyre has actually a slightly greater radius than a 190 (think its about 4mm or so more) so a new 190 should give greater clearance than a new 180.
Like yours my eccentric was in the correct range of adjustment so I was a little baffled. I ended up losing patience with it and ordering a 96 link chain to lengthen the wheelbase a little. It actually lengthened it quite a lot and a then couldnt get my chain tight enough! Not a major problem as I wanted to lower the gearing anyway so I went up 3 teeth on the rear (instead of fitting the 14t sprocket I already had) The end result was the tyre was just a little further back than it was when I started. Worked out pretty expensive with new Tsubaki chain and Renthal rear sprocket and carrier. Promptly did a track day at Oulton that stretched the new chain enough to increase clearance a little more after adjustment. Happy with it now.  |