Pushrods keep dropping

Discussion in 'Other Service and Maintenance' started by Pigpen, Aug 29, 2010.

  1. Pigpen

    Pigpen New Member

    My front exhast pushrod keeps dropping, I readjust it fire up the bike the bike gets warm and the pushrod dropps again. Anyone have this problem?
    What do I do to fix it?

    2006 Special Construction with a 96cc ultima evo
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    What do you mean by that? Are the threads on the adjuster screw or the internal threads in the rod stripped? If so, new rod (s).

    Otherwise, is your lifter not pumping up?

    If the latter, check your tappet filter screen to make sure it is clean. As a quick check on the lifter, you can swap it with the one next to it and see if your problem moves. That would point towards new lifters.

    BTW, you are adjusting your rods to zero lash and then at least half the lifter piston travel, right?

  3. biscuit

    biscuit Junior Member

    How about if your'e adjusting your pushrods before the lifters have bled down?

    My understanding is that you should wait 20 or so minutes for them to bleed down before you adjust your pushrods.Then you adjust them so you have free rotational movement,but no vertical movement.A fine line.
  4. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    This is sorta right. But here is the quick and dirty:

    1. Disconnect negative lead on battery
    2. Pull spark plugs
    3. Jack up rear wheel
    4. Put tranny in 4th/5th
    5. Collapse the pushrod tubes
    6. Collapse the pushrods
    7. Let the lifters expand so piston is at full height
    8. Rotate engine until exhaust opens/closes and then intake opens/closes
    9. Find TDC on that cylinder (compression stroke)
    10. Adjust both rods to zero lash, then half piston travel (or a little more)
    11. Lock jam nut
    12. Wait until pushrods can be rotated "easily" with thumb and finger
    13. Move to next cylinder and repeat
    14. Resecure pushrod tubes
    15. Turn engine over by rotating rear wheel listening for "bad" noises
    16. Reconnect battery
    17. Turn engine over with starter listening again
    18. Reinstall plugs and back it out.

  5. Pigpen

    Pigpen New Member

    Thanks for the advise everyone. Pulling it back out tomorrow for round 3
  6. Tramp60

    Tramp60 Member

    I've always made sure piston was at TDC on compression stroke ( both intake and exaust closed) Then adjust pushrods to remove all up and down slack. Then four full turns down ( lengthen), wait 15 to 20 min. and readjust pushrod to where there is no up and down play and you can roll the pushrod with your fingers. Providing your running hydraulic lifters? Never tried TQuentins way of rotating motor half piston srtoke. Actually sounds a little easier. Hmm, learn something new every day. I love this place. Thanks TQ!
  7. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    The number of full turns that you use is dependent on the tpi of your adjuster. See here:

    Calculating the Adjustment

    The PRs should identify the tpi for the adjuster end. Let's call that X. So each complete turn of the adjuster is 1/X inches increase (or decrease!) in the length of the PR. So as an example:

    24 tpi = 1/24th inch per turn or .0417"/turn
    28 tpi = 1/28th inch per turn or .0357"/turn
    32 tpi = 1/32nd inch per turn or .0313"/turn

    Now as a general rule, to figure out the number of turns you would divide half the lifter piston travel by the number of inch/turn to give you number of turns.

    Another method is to multiply the tpi times half the lifter piston travel. In the case of the "B" lifters, since this is a nice figure of 1/8" or .125", we multiply that times tpi to give you this:

    24 tpi = 3 turns
    28 tpi = 3 1/2 turns
    32 tpi = 4 turns

    This last method is the easiest. So if you want a different adjustment besides half the lifter piston travel, it is exactly the same process; that measurement times the tpi = number of turns.

    Since the adjustable PRs will have hexagonal nuts on the end of the rod part, each flat is 1/6th of the movement noted above or the following fraction of turns per flat:

    1 flat = 1/6th = 0.167 turns
    2 flats = 1/3rd = 0.333 turns
    3 flats = 1/2 = 0.500 turns
    4 flats = 2/3rd = 0.667 turns
    5 flats = 5/6th = 0.833 turns

    So if I wanted to adjust my 24 tpi PRs to 0.140" out, it is:

    24 x 0.140 = 3.36 turns

    3.36 turns is approximately 3 turns and two flats!!

    Adjusting Pushrods - Harley Davidson Community