Check for "milky" oil (water contamination) and ensure the coolant is full and clean.
Wiggle wheels, swingarm, and head stem; any play or "clicking" indicates worn bearings. buying a used dirt bike checklist
Inspect welds for hairline cracks or deep paint creases, which signal a major crash. Check for "milky" oil (water contamination) and ensure
Pull the cover; if the filter is filthy, the owner likely neglected critical maintenance. and head stem