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Lash caps. Any good?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Fast Eddie, May 18, 2019.

  1. Fast Eddie

    Fast Eddie VIP MEMBER

    Oct 4, 2013
    Thanks Mike, if the lash caps were eroding the valves that would seem to demonstrate fretting / movement at high RPM... which is exactly what I am concerned about with lash caps. Wear is not such a huge concern on a track bike, but fretting and movement often = potential failure !
  2. jseng1


    Nov 26, 2009
    The tappet below could be what you're looking for - If you're willing to make your own (or reshape an existing bolt head) and harden the bolt to the original tappet screw specs.

    It uses a hardened 1/4" Fine bolt that just barely fits inside the original threaded hole in the rocker tip. Its held tight with the nut only and tappet adjustment is made with interchangeable slotted washer shims. A large diameter mushroom tappet would break but the tappet in the photo won't because it is supported.

    I came up with this to extend the effective rocker arm length for increasing the intake valve lift (and to move the intake valve instead of just re-angling it. More info at:



    I haven't taken this any further than the design stage. You could make the radiused bolt head a larger diameter than the one shown in the photo.

    PS - Fast Eddie - I've raced with the lash caps and run them on the street for tens of thousands of miles and I have never had one fail (even if there was wear on the surface or a little minor fretting on the valve tip). If they eventually wear they are easy to replace. I've never seen one get too loose on the valve tip. Sometimes they press on so tight (depending on valve tip diameter) that the problem is getting them back off.
    Last edited: May 19, 2019

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