This is the AF1 Racing recommended alternative to the OEM spark plug (part number 438074 ex 8515053)
Aftermarket Spark Plug CPR6EB-9
For 2000-2008 SR50 Ditech/Factory
This extended electrode plug reduces the chances of plug fouling and is two heat ranges hotter for more performance, and a complete fuel burn.
Gap should be set at: 0.9 mm (0.035 in.)
This plug works best on the Morini engined SR50. Morini engines will have the RH engine cover as seen in the image below: