When dual plugging engines, it is necessary to retard your timing by about 5 degrees, in most cases, to achieve the best results. This is necessary because by adding an additional spark on the opposite side of the combustion chamber you will speed the burn of fuel and in essence advance your timing. Different heat ranges of spark plugs can also have an effect. Extended tip spark plugs will burn fuel quicker than standard or recessed tip plugs, because they are out in the chamber further. Timing, spark plug, heat range and jetting should be done by a good tuner for optimum results.










Source: jpcycles