You should get a set of main jets and go up in size significantly until it runs too rich, then start going down until you find the sweet spot. You might need to raise the needle too if it bogs when you twist the throttle. You will probably notice problems when running abt half throttle if the needle is wrong. Keep an eye on the plug when you are jetting, if you have some experience in jetting, the feel and sound of the engine will tell you when you are close. I sometimes use Chinese jet kits and think they work ok, especially for the price, but you can't compare the numbering on them with anything else, you have to stay with that kit when you are jetting.
