Kubota — Correcting Valve and Valve Seat
Repair & overhaul · Valves and valve seats
From a Kubota service manual covering: Hurth HBW 100, Hurth HBW 125, Hurth HBW 150, Hurth HBW 250, Hurth HBW 35, Hurth HBW 50, M-25XPB, M-35B, M-40B. Check it applies to your exact model before use.
Browse Kubota generators & specs →
Procedure
- Check valve stem and valve guide I.D. and repair if necessary.
- Correct the valve with a valve refacer.
- Slightly correct the seat surface with a 60 deg (intake) or 45 deg (exhaust) seat cutter.
- Resurface with a 30 deg cutter (intake) or 15 deg cutter (exhaust) to specified width.
- Inspect for even seating; lap with compound using a valve lapping tool.
- Check the valve seating with prussian blue; contact should be good all around.
- Be sure to check valve recession after correcting the seat.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Valve seat width: 0.0835 in. (2.12 mm)
- Valve contact must be 70% or more
Source: Kubota service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.