Honda GX 120 Tech Manual page 8

Exhaust 16 grams minimum
C. Drawing of valve dimensions (Intake Valve followed by Exhaust Valve)
Note: UT-1 (Current 120) ex valve part # 14721-ZF0-000 – Retainer # 14773-ZE1-000 and lash cap # 14781-
ZE1-000 must be used in combination. UT-2 (New 120) ex valve part # 14721-Z4H-00 and –Retainer #14771-
ZE1-000 must be used in combination (no mixing of old and new style parts) New style ex valve 14721-Z4H-000
measures 2.470 overall length
HEAD
Cylinder head will be in "as cast" and in factory machined condition and there must be no addition of metal or any other
substance to the inside or outside of the cylinder head. No alteration that could increase valve spring pressure. Note:
Cylinder Head gasket surface is non tech Effective 4-1-11 Thailand heads will no longer permitted on the GX 120 engines.
Any legal Japanese GX120 head may be used. New Gx 120 casting number 13 heads are available from HPD).
A. Measure from flat of head surface down to valve seat. This dimension will be:
A1. Latest head cylinder number: 12210-ZH7-415
Maximum 0.265" Minimum 0.250"
B. Measure from surface of head to top of valve guide.
This dimension will be: 0.925" Max.
Intake 0.925 Max.
Exhaust 0.925 Max
.
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