compression problems

Discussion in 'Dyna Models' started by georgep0163, Sep 29, 2011.

  1. georgep0163

    georgep0163 New Member

    3
    0
    0
    hi my 99 dyna super glide is giving me a heck of a time its a stock 1450 with 20,000 miles front jug has 80 psi while the back has 160 psi lap the valves honed the jug and installed new rings any ideas would be thankful. runs great under a load pops here and there when coasting
     
  2. TQuentin1

    TQuentin1 Well-Known Member Staff Member Moderator

    4,633
    83
    101
    Adjustable PRs? If so, would suspect adjustment.

    Did you stagger the new rings? Did you follow Gliders recommendation to seat the new rings?

    Harley Davidson Community

    Blown head gasket? Valve hanging? Broken compression ring? Broken valve spring?

    Do a leak down on that cylinder to see if it is sealing. Then start eliminating from the easiest to the hardest!!

    TQ
     
  3. georgep0163

    georgep0163 New Member

    3
    0
    0
    thanks new gaskets springs fine did the head first valves are fine rings are new cant get the compression over 80 no smoke at idle skips cly is running cooler than back jug if i take it for a ride it seems to be firing but at idle its like it not getting fuel in the front jug thanks 4 your reply so fast
     
  4. eleft36

    eleft36 Junior Member

    441
    26
    1
    Exhaust push-rods located outside rear and outside front ?

    Al


    :USA
    :CONNECTICUT
     
  5. Piedmont

    Piedmont Member

    7
    0
    0
    In the aviation world we find the leak (and that's what it is) by putting air into the cylinder and listening in the crankcase (dipstick) for rings, exhaust for exhaust valve and induction system for intake valve. It's easier on an aircraft engine because we can use the prop to hold the piston at top dead center, but you can figure a way to do it I bet. Punch the center out of an old spark plug and weld an air fitting on it to connect the air through a regulator. Bring the pressure up slowly while holding top dead center and you'll hear the air leaking from where ever the problem is.

    This procedure requires a little equipment to accomplish but I guarantee you'll find the problem. I have a gizmo that measures the amount of leakage but you don't need to know that, just where it is leaking. Do the good cylinder and compare.

    Good Luck,
    Piedmont
     
    Last edited: Oct 3, 2011
  6. georgep0163

    georgep0163 New Member

    3
    0
    0
    thanks everyone been working havent had a chance to try this stuff but im going to real soon im losing nice weather
     
  7. 70_West

    70_West Member

    87
    0
    2
    Sounds like Piedmont is on the money. I usually squirt oil in to the cylinder and do a compression test to eliminate the rings, if it comes up, bad rings... if not, I look hard at the head.

    I like his method much better! I bet a fellow could figure a way to put low pressure through a screw in compression gauge hose and isolate the problem quickly.
     
  8. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    COULD you have bent the valves when you adjusted the pushrods? OR set up Too tight,,, staying open and not closing all the way??? OR is all that STOCK???

    If you didn't allow the time needed to BLEED Down lifters Before moving on (IF adjustable push rods) ,,,the piston could of Bent the valves a little and causing them Not to seat now..

    I don't think a set of rings would Loose That much pressure but That is Just Me thinking.

    signed....BUBBIE
     
  9. Jack Klarich

    Jack Klarich Expert Member

    18,544
    153
    399
    You say one cylinder is cold? Compression low? Bent valve, blown head gasket, push rods Tooo tight would be a good place to start, tear that head off again:s
     
  10. BUBBIE

    BUBBIE Well-Known Member

    4,959
    83
    113
    Another Thought.... DID you and are you sure the cams are aligned correctly???

    Being down that much compression is what One Tooth Off on the cams would do...:(

    signed....BUBBIE