I just bought a used 2002 KX125 for my son. Bike seems in good condition and came with FMF Fatty Pipe and Silencer. My son is coming off a Honda XR100 so this will be an adjustment. I think he's ready since he has pretty good riding skills, is 5'9" tall, and rides fine on my KDX. We won't be racing. We play ride some MX and trails. Anyway, my question concerns spark plug heat range and jetting. Bike came with a NGK B9EG plug. I don't know what jets are installed, haven't gone into the carb, and previous owner kept no notes. Also, didn't get an owners manual with the bike, previous owner is looking for it. I ordered a service manual earlier today. My specific questions are: 1) Is the NGK B9EG the correct plug for this bike? 2) What heat range would you recommend for nonagressive riding? 3) What jetting would be correct for play riding ( based on 500 ft elevation and 70 degrees F)? Any help is appreciated. We wet fouled a plug earlier today while riding around the house. Thanks!
