Websterfam

HI. ..probably a topic that's been discussed at great length so apologies in advance. Just purchased a DT125LC monoshock and not sure of year. Trying to set the carb and must admit to being extremely worried about causing engine damage due to fuel being to rich or lean. Bike doesn't pull away decently in first but then goes like a bat out of hell above 1st. Bike is premix at 33:1 . Have fuel screw at 1 3/4 turns out. All suggestions on air screw and other settings will be much appreciated. Also should I fit a decent airfilter as the one fitted is just a bit of stocking by the looks. Many thanks