2008 Yamaha Raptor 250SE / 250SE2 Factory Service Manual, Page 292Get this manual
CHARGING SYSTEM EBS01066 EBS01100
3Charging voltage Connect the engine tachometer to on to the ignition coil Connect the pocket tester (DC 20 V) to the battery as shownPositive tester probeNegative tester probenegative battery terminal
positive battery terminal