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Thread: Difficulty starting a rebuilt 48 Panhead FL - Part 3

  1. #1

    Default Difficulty starting a rebuilt 48 Panhead FL - Part 3

    Hi Guys

    I'm still having problems on this one - since the previous thread, I've had a rebore done with new pistons and compression is now up at 100 psi on both cylinders.

    I'm having problems starting her. She splutters for a few seconds but doesn't catch on.

    I've never had the bike running and this is my first Harley so I need to check a few things;

    Timing is spot on, it has the later auto advance unit, points gap is correct, and timing has been checked when advanced.
    Spark Plugs are new Champion J12YC, gap correct, sparks ok
    Timing gear marks all line up
    It has solid pushrods, adjusted properly
    Inlet manifold has been removed cleaned and new brass packing bushings fitted, greased - pressure tested - all ok
    Inlet nipple holes sealed - pressure tested - all ok
    Heads removed, valves lapped in and each cylinder checked at 100psi.
    Heads are from 1950, not 48.
    The carb is an M-74, not the original, teamed with the 1950's manifold, with the two carb gaskets and plastic insert. The carb has been cleaned, float (brass) level checked with float bowl off carb to be 1/4", fuel level checked as 5/8" from top of bowl, butterfly valves checked, airways blown out etc etc, no fuel leaks.
    Petrol flow to carb is good, idle needle backed out 2-5 turns (tried variations), high speed needle backed out 2 turns.
    I've also done a leak down test on compression stroke and there do not seem to be any gasket leaks.

    I am following the starting process; 2-4 kicks ignition off, choke closed, throttle wide open, then ignition on, choke 1/8 - fully open, throttle 1/3 open, and all other variations!

    My guess is it has to be the carb, as it sounds like petrol starvation, and as everything else seems OK, but beyond putting in a plastic float, I'm guessing.

    Any ideas????????
    Last edited by harleygreg; 08-02-2019 at 01:46 PM.

  2. #2
    Join Date
    Jun 2001
    Central Illinois, USA


    Honestly, Greg,..

    You could get it running 'good enough to sell' by setting the brass float down to 3/8" for a made-in-India float,
    or .410" for a Kokesh with two flat dimples on the bottom.

    PS: If its an India float, better shake it and listen for fuel inside.

    PPS: I took a sloshing Keihin float out of a customer's machine in the early '80s that was the hard-plastic kind.
    I've still got it, and it still sloshes.
    Gas got in; Why can't it get out?
    Attached Images Attached Images
    Last edited by T. Cotten; 08-02-2019 at 03:26 PM.
    AMCA #776
    Dumpster Diver's Motto: Seek,... and Ye Shall Find!

  3. #3
    Join Date
    Jul 2010


    You mention all mechanical, how is everything in the electric circuit? Battery fully charged, gen polarized and not shorted, any key switch shorts, condenser correct and good? Are the plugs wet or dry when it doesn't start? Try disconnecting everything from the key switch except what is needed, all lights, oil switch etc. I just talked to a friend of mine this morning, doesn't matter but also a '48, and every time he went to stop the bike would quit, ended up being a shorted brake switch. Good luck.
    Bob Rice #6738

  4. #4


    good points, I need to check this by running a wire direct to the coil. Done it before but you never know! On the condenser, I've never had one fail and there is no arcing on the points, but I do have another one. I'll check it out - Thanks

  5. #5
    Join Date
    Sep 2005
    Sarasota, Florida


    I've had 2 condensers fail and it can give you false diagnoses. You can really chase your tail with electrical problems. When you do find the problem, please let us know as it is always good to have trouble data.
    Eric Smith
    AMCA #886

  6. #6


    Ok - Demonic laughter as the 48 fires up and keeps going - what a great sound and music to my ears!!!!!!

    So, it was the condenser, and a lesson well learnt. The 'old' condenser provided a spark at the plugs which was good and regular and I had tested the condenser against the test routine given below. This condenser gave the spluttering erratic start. However, I recently took delivery of the correct timer for the 48, which I've refurbished which also had a condenser. On testing the 'new' condenser, with the guide below, it showed different characteristics in that there was a more gradual increasing and decreasing of resistance during the two tests below.

    I swapped it out and the beast started first time, revved, idled etc etc

    Many thanks - still a lot to do but a major step forward.

    Condenser testing
    Remove the condenser from the engine. Place the condenser on an insulated wooden surface such as a workbench. A metal surface may cause the test to fail. You will note that there is a small metal connector located at the top of the condenser. This connector is the "hot" or power connection. The metal case of the condenser is the ground point.
    Switch the volt ohmmeter to the ohms position. Place the red lead into the "ohm" connector on the meter. Insert the black lead into the "com" or common connector on the meter.
    Touch the red lead to the hot connector on the condenser. Place the black lead to the metal case or ground point on the condenser. The meter's deflection needle should have jumped slightly to the right. The needle may also slowly rise in the right hand direction. Hold the leads in place for 15 seconds to 20 seconds. This action places charge to the condenser.
    Remove the leads and reverse the placement to the condenser. In other words, move the red lead from the hot connector to the metal case, and move the black lead from the metal case to the hot connector. At the moment where both leads are touching the correct points, the meter should jump towards the right. This action discharges the condenser.
    Movement from the meter's needle indicates the condenser is good. If no movement was indicated on the meter in either circumstance, the condenser is bad and must be replaced. Retest the condenser several times for a consistent reading.

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