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2-51 2 ATV-0107 Measuring Valve Guide/Valve Stem Clearance 1. Using a micrometer and small bore gauge, take diameter readings on the valve stems and inside the guides. 2. Determine the stem clearance inside the guide. NOTE: Be sure to take readings at more than one place along the length of each stem and guide. Lapping Valves NOTE: Ensure that all carbon has been removed from the valves. 1. Using a valve lapper, produce a contact pattern on each valve face by applying a uniform coat of valve lapping compound to the valve seat and by rotating and tapping the valve head. 2. Acceptable width of valve seat contact width (measurement A) is within a range of 0.8-1.0 mm (0.032-0.039 in.). GEN-0023 GEN-0024 NOTE: Do not grind the valves. If a valve is dam- aged, it must be replaced. 3. Lubricate each valve stem with lightweight oil; then apply a small amount of valve lapping compound to the entire seating face of each valve. 4. Attach the suction cup of a valve lapping tool to the head of the valve. 5. Rotate the valve until the valve and seat are evenly polished. 6. Clean all compound residue from the valve and seat. Valve Seat Repair NOTE: If the valve seat is beyond servicing, the cylinder must be replaced. GEN-0025 ITEM SPECIFICATION Valve Guide/Valve Stem Clearance Intake (max) 0.080 mm (0.0031 in.) Exhaust (max) 0.100 mm (0.0039 in.) |