ok so i have a 91 lt250r bored over 50 with a fmf powercore pipe what should the maine jet be ?also it has a 13t front and 40t back gear what is the top speed ?
What carb? Elevation? Ambient temp? Airbox setup? Those are the first few questions to get you pointed in the right direction. Nobody will be able to give you an exact size.
Some of the 250 guys will chime in to tell you what ranges of jets and needle settings to start with. Then you just gotta experiment. Good luck
I ran a 195 main and 35 pilot jet with stock ports kn filter and .50 over boysen rad valve and fmf setup. I live around 2000 feet and ride up to 4000 feet. Winter I ran a 205 or 210 main. Which it ran fine for me.