What size jet

My KX250 96 mod is running rich at 50/1 mix ratio. The main jet is a 158, should I go up as in higher number jet or lower to lean it?

Not fouling plugs untill lately. I ride my practice track usualy as hard as I can go, it has straits, sx style corners and a couple of doubles. I rode it Saturday morning and it ran strong but still with more smoke than I want to see comming out of it. The commpression is top notch, I pulled the reeds and they look great, pulled the carb and every thing is clean. I keep up my air filter using no toil oil and cleaner. I went to ride it Saturday evening and kicked it, it fired right up, as I went to give it a little throttle and it bogged, I let off of it and it popped a couple of times and cut off.