Tip on Valve Seat Grinding

Discussion in 'Motorbike Technical Discussion' started by Nomen Nescio, Oct 12, 2005.

  1. Nomen Nescio

    Nomen Nescio Guest

    First, use some prussian blue and observe where the old seat contacts the
    valve face. If the old seat is on the valve face with no overlap, then
    proceed with the simplified procedure below:

    Use a 15 degree stone and cut the old seat in half.
    Grind the new seat. You want intakes to be the width of a dime and the
    exhaust the width of a penny (nickel in the case of auto engines).
    Finish by using grinding fine grit grinding past to lap the valves.

    Check your work by pouring solvent into the inverted combustion chamber
    with the spark plug installed. There should be no leakage through the

    You will find the new seat meets the valve face in the same area as the old
    seat. This procedures saves countless trial and error grindings to get the
    seat in place at the correct width.
    Nomen Nescio, Oct 12, 2005
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  2. Anyone who follows any of NN's procedures deserves what he gets.

    R. Pierce Butler, Oct 12, 2005
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  3. What, you never heard of a 3-angle or 5-angle valve job? It figures.
    krusty kritter, Oct 12, 2005
  4. Nomen Nescio

    Hank Guest

    breaking my own rule about feeding trolls; be wary of taking tech advice
    from someone who has asked as many moronic q's as this bird...........

    Hank, Oct 12, 2005
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