At idle the fuel is pulled up using engine vacuum the main jet circuit uses the vacuum or negative pressure of air pulled through venturi. If too large carb is used the negative pressure is reduced which is why larger jets have to be used to compensate the lack of neg. pressure. Not only do you run lean at WOT, the transition from idle jet to main jet will be weak causing a flat spot. Make sure your stock carb is clean leaving the .38 pilot jet in and increase the main jet to a 125 than do a WOT run and check plug. Now as I said use an old already colored plug when doing this check. Pay attention to the ceramic and rim of threads for color, no need to cut up plug to check. One run will change the color of plug but it has to be an already used colored plug. Once you determine the proper main jet @ WOT than you will adjust if necessary the pilot jet. The smaller the sprocket the more top end, the larger the sprocket the more low end. The larger the tire the more top end the smaller the tire the more low end. Work on one thing at a time so you can determine the changes made from that particular adjustment. More than one change at a time and you cannot determine what caused what change.
|