Had exactly the same thing happen on my bog stock 999 mono at Bruntingthorpe a couple of weeks ago - speedo climbed to 174 then went blank but for three horizontal bars.
This blanking of the speedo above 174 also erased the lap timer data too, so I did several more runs holding the speed at around 172/173 mph. This time the lap timer indicated a max speed of 162, which I think reflects the 7% speedo overread indicated in the users manual. From memory the max engine speed recorded was about 1,000 rpm short of the limiter.
The bike was still accelerating (slightly) as it passed 174 (162 mph true), so perhaps it is capable of a genuine 165 as measured by a couple of bike mags.
For the record: my bike still has stock gearing - and the weather was sunny with no wind.
it was still pulling hard for another 1k revs one sweet motor better than my old 996r/998r
only problem is that it won't wheelie off the power in second! (have to go up through box from 1st) reckon i will follow the 1 tooth off the front route!