I had this myself a long time ago, The bike was going well, Then i fitted a Gold star silencer and went on a long run, Met a friend on the road and had a bit of fun !!, It started eight/ stroking at about 100. The thing is , If you redo the jets in the carb' You can get it to run fine, It won't be as fast, But you can put it back how it was after the MOT. Cheers Bill.