2008 Yamaha Rhino YXR70FX Factory Service Manual, Page 91Get this manual
CHECKING THE SPARK PLUG
5Check: electrode Weardamage Replace insulator Abnormal color ReplaceNormal color is medium-to-light tan color6Clean: spark plug (with spark plug cleaner or wire brush) 7Measure: spark plug gap Use wire gauge or thickness gaugeOut of specification RegapSpark plug gap 0.80.9 mm (0.0310.035 in) 8Tighten: spark plug