2006 Arctic Cat Y-6/Y-12 50cc and 90cc Service Manual, Page 40Get this manual
2Using calipers, measure the valve stem diameter that it is within specifications NOTE: To produce the proper 60 cross-hatch pattern, use low RPM drill (600 RPM) at the rate of 30 strokes per minuteIf honing oil is not available, use lightweight petroleum-based oilThoroughly clean the cylinder after honing using mild soap and hot waterDry with compressed air; then immediately apply oil to the cylinder boreIf the bore is severely damaged or scored, replace the cylinder
3If any measurement exceeds the specified limit, the cylinder must be replacedMEASURING VALVE SPRINGS
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NOTE: If the valve stem diameter is not within specifications, the valve must be replaced
Using calipers, measure the free length of the valve springsIf any spring is not within specifications, it must be replacedMEASURING CAMSHAFT LOBE HEIGHT
MEASURING ROCKER ARM TO SHAFT CLEARANCE