Description
Rocker arm kit fits 139F 31cc engines, Honda GX31 engines and UMK431 strimmers/trimmers/brushcutters. The rocker arms pivot on the rocker shaft in the cylinder head, converting the lifting motion of the camshaft into direct downward pressure on the intake and exhaust valve stems, opening each valve at the correct point in the engine cycle. When a rocker arm becomes worn, its pivot bore loosens, or the contact surface pits, valve clearance changes and the valve may not open or close fully, leading to reduced compression, valve tapping noise, hard starting, or loss of power. Fitting a replacement rocker arm kit restores correct valve actuation and valve clearance, allowing the engine to run properly again.
Fits specified models:
- 139F 31cc engines
- Honda GX31
- Honda UMK431
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