Wal-Mart has the 4312+2 Platinum plugs for sale at 9 bucks for two and there's a rebate so you can get 3 bucks back. That's a net price of 12 bucks for four plugs. Good deal on a good plug. The 4312+2 is exactly the same plug as the 4419+4 with two less ground electrodes.
The 4312+2 Platinum is the highest heat range of this series at #9 heat range. This is an equivalent heat range to the OEM NGK IFR5L11 Iridium plug that is standard on every 1800 after 2003 and is the same heat range as the Bosch 4419+4 as per a Bosch factory engineer and their manual. They are all a heat range of #9 which is the practical limit for the VTX if the A/F ratio is where it should be.
FYI............Having more ground electrodes makes no difference in performance as there will be only one ground path during a spark cycle event. Actually, having more grounds surrounding the center electrode can actually impede flame ignition by shrouding the spark from the center of the chamber. From a performance view point, it's only beneficial to have more than one .............if one was to break off. If that happened............you've got more problems to worry about than how many ground electrodes your plug has. With this in mind...........never attempt to adjust the gap on a +2 or +4 plug as the ground electrode could be weakened or broken off. This a precautionary statement from Bosch. There's no need to adjust it because the spark travels across the nose of the insulator on this type of plug. Bosch offers the +2 and +4 with that many grounds in an effort to maintain the correct spark gap for a longer life span of the plug. It has nothing to do as far as an outright performance enhancement. In a perfect world and in theory, the +2 and +4 plugs should maintain spark gap and optimum performance for a longer period of time versus a single ground Platinum plug, before they need replacement. The +2 and +4 plug series is a cheaper way of getting somewhat longer plug life, which is the benefit of what an iridium plug would do for you if you spent the money for one.
That said........... many people run both the +2 and +4 without any issues at all. Run what makes you feel good. I run the +2 and they run no different than the OEM plug.
