William Dunlop says he will take some time to 'recuperate' after quitting this year's TT.
The 32-year-old Irish rider withdrew from the event yesterday citing personal reasons.
In a statement he said: "This is a very difficult decision and not one I have taken lightly, I can only apologise to the team and all of our sponsors but I believe that continuing would be the wrong decision and would not give a true account of either myself or the team.
"I would like to thank Tim especially for how understanding and supportive he has been over the past few weeks, I obviously feel like I have let him and the team down but they have stood by me throughout.
"I am going to head home and take some time to recuperate before making a decision on when I will be back on the Temple Yamahas."
Team Boss Tim Martin said his decision was 'extreamly disappointing' saying he'd been looking forward to working with William for some time.
He added: "There is no race in the world however where having 100 per cent focus and commitment is more important so it is the correct decision in the end for William.
"Hopefully after a few weeks off he will come back stronger, we all know what a natural talent he is so having a fit and well William back to fight for wins at the Ulster Grand Prix is now our focus."