ORIGINAL: kx250ryder

Buy a temp. gauge (if you don't have one) and. . .

1.) Reset needles to stock settings (you may need to lean slightly over break in settings to keep car running)
2.) Warm car up until chassis gets hot, making sure temps never exceed 250
3.) Lean HSN to keep temps between 220-250 making sure smoke is visible between low to mid RPMs
4.) Lean LSN until pinching fuel line near carb causes engine to stall between 3-5 seconds
5.) Check to make sure low end changes haven't made motor exceed 250, if they have richen HSN
6.) Adjust idle as high as you can without car stalling.
7.) Re-check above any time outside weather changes significantly, or at the beginning of a day of driving

If you don't know the stock engine settings, try setting your LSN and HSN to 3 turns out. If you have a three needle carb, set the MSN (I forget the actual name) to flush. This needle can be tricky though, as the stock settings are often calibrated from the factory, and generally shouldn't be changed until you have mastered engine tuning (maybe not even then).