Keep in mind that there's a very hard jump to do just after that part, and if you fail, you have get past that belt part again. However, when playing with the Turtle Speed Mode (by pressing T midgame), this spot becomes a whole lot easier, because you don't need to worry about timing so much. Practise a lot and you will do it.

If anything fails you can cheat to get an airboard and just fly through it though.