hi having a bit of bother with my sons 07 125 rev 3 .its developed a really gutless flat spot just above tickover but when its reved above this its fine also wont tickover .ive cleaned the carb ,airfilter and new plug but cant think of anything else .anybody any ideas

the needle could be loose or the carb manifold could have a leak??????

I couldn't say for sure about the 125, but the bigger Betas are sensitive to the exhaust system condition. I would clean the mid muffler and repack the silencer. It makes a huge difference on my 270. I would guess than the smaller bike is even more sensitive.