F510 & F525 Carburetor – SERVICE BREATHER
NOTE: Breather valve assembly is located in cylinder heads of PA420A and PA540A engines.
1. Remove rocker arm cover.
2. Measure air gap between reed valve (A) and valve seat (B) at valve tip. Replace reed valve if gap exceeds 1—2 mm (0.040—0.080 in.).
3. Remove breather valve assembly (C).
4. Inspect breather for sticking, binding, cracks or distortion. Replace breather if worn or damaged.
5. Inspect valve seating surface. Surface must be free of nicks or burrs.
6. Install breather assembly.
7. Check that drain back hole in cylinder head and block is open.