Caution: If the guides are worn, replace them before replacing the valve seats.
2. Carefully cut the seat at 45°, removing enough material to ensure a smooth and concentric seat surface.
3. Cut the top edge of the seat with a 30° cutter and the bottom edge of the seat with a 60° cutter. Check the width of the contact patch.
4. Make another very light pass with the 45mm cutter to remove any possible burrs caused by the other cutters.
Valve seat width:
Default value:
- Inlet: 0.85 - 1.15 mm
- Release: 1.25 -1.55 mm
Limit value:
- Inlet: 1.6mm
- Issue: 2.0
5. After restoring the seat, also check the valve:
Apply "Perlin glaze" to the valve bevel and insert the valve into its original position in the head, then press it onto the seat and rotate it a few turns around its axis.
6. The contact patch of the valve with the valve seat should be in the middle part of the seat.
- If the contact patch is too high (closer to the valve stem), You need to use a 60° cutter to "move" the contact patch down and then another 45° cutter to restore the seat width.
- If the contact patch is too low (closer to the edge of the valve). You need to use a 30° cutter to "move" the contact patch up, then another 45° cutter to restore the seat width.
Note: The final finishing should always be done with a 45° cutter.
7. Insert the intake and exhaust valves into the head and measure the installed height of the valve stem.
Installed height of valve stem for intake and exhaust valves:
- Nominal value: 53.17- 53.64 mm
- Limit value: 53.89 mm
8. If the valve stem installation height is outside the standard value, replace the valve and recheck. If replacing the valve does not change the result, replace the cylinder head (the valve seat in the head is set too deep).
Replacing valve guide bushings
Caution: Heat the cylinder head to 150°C before removing or installing the guides.
Caution: Use gloves when handling a hot cylinder head.
1. Knock out the valve guide bushing from the cylinder block side.
2. Press in the new valve guide to the specified depth.
Valve guide bushing installation height:
- Intake: 17.85 - 18.35 mm
- Issue: 18.65-19.15 mm
Deployment
Caution: For new valve guides only.
1. Coat both the reamer and the valve guide with engine oil.
2. Rotate the reamer clockwise along the full length of the valve guide bore.
3. Continue rotating the reamer clockwise as you move it away from the hole.
4. Rinse the guide completely in detergent and water to remove any remaining chips.
5. Check the valve clearance.
[Publication reprinted from the website: HondaBook.ru]