Your looking at buying an 86 or main jet size and if it a carb where the idle set screw is sealed, you will need to unseal and possibly give it one turn out. That's a ball park because depending on conditions of engine load and temperature in your local, you have to fudge the mixture richer or leaner as the case may be. The thing to keep in mind is you will want to get a new plug and after a short ride, look at it for color. There are online sparkplug charts to guide you however I would describe the correct plug color as a dark tan.
Hope this helps, Good Luck.
Last Edit: Jun 5, 2013 23:32:02 GMT -5 by dadzilla