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Engine turns but does not fire

Discussion in 'Motorcycle Tech Talk' started by Remo, Sep 12, 2005.

  1. Remo

    Remo New Member

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    Having a problem with my 78 shovel head, engine turns but does not fire... Checked all the obvious plugs, wires, coil and new set of points. Problems been on and off. Starts and dies (looses spark).
    Remo, Sep 12, 2005
    #1
  3. chucktx

    chucktx Moderator Staff Member

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    you stated you checked all the obvious.....are you getting spark....all the way to the plug. are you getting air....are you getting fuel all the way to the cylinder. next would be is the spark arriving at the correct time. the same with the fuel. that would intail the timing. also how is the compression. are the cylinders close to the same pressure. as far as the on off on the engine running, how is the electrical system to the ignition side of the engine....no rubs in the wires, loose connections, circuit breakers kickig in and out...need more details.....hope this helps a bit
    chuck
    chucktx, Sep 12, 2005
    #2
  4. hotroadking

    hotroadking Super Moderator Staff Member

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    1) check for fuel delivery, make sure it's getting to the carb and the engine
    2) Check for compression, make sure you have plenty in both cylinders
    3) Check for spark

    If you have all 3 then ignition might not be firing at the proper point, time it to TDC and start from there.
    hotroadking, Sep 13, 2005
    #3
  5. bikerbarbie883

    bikerbarbie883 New Member

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    I have done all the obvious and then did the TDC still won't fire......PLEASE HELP
    bikerbarbie883, Sep 15, 2005
    #4
  6. maxpower_hd

    maxpower_hd Active Member

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    I don't want to sound insulting. I just don't know how long you have had a Shovel or how familiar you are with points. I don't deal with them a lot myself.

    Have you double checked the gap on the points? Are the points possibly defective? I have seen brand new ones not work very well. We had that problem not too long ago on a 1983 Shovel with a Morris magneto and kick only. We just couldn't seem to get the new points to work right. We put the old ones in and it fired up, just not every time. We got another new set, gapped them and they were fine. The brand new ones previously installed were indeed defective. Upon closer examination, the defective ones would not meet squarely. They were sort of offset. The old ones and the new replacements met squarely. I'm not sure if that was it or not but They work fine now.

    We also re-timed it and now it kicks after just one or two kicks........as long as he doesn't flood the thing. :rolleyes:

    Good luck! I would be interested to hear how you make out.
    maxpower_hd, Sep 16, 2005
    #5
  7. CD

    CD Guest

    Points are actually easy to work with....unless they are bent or arced or the capacitor is bad. Points cannot be bent to where the open or close unevenly or the coil will have no time to build up (dwell) and will only provide a weak spark at best.

    I would get another set of points and capacitor or have those checked. Ohm out the coil, check the spark plug wires and get new plugs make sure that you have a full 12.5vdc voltage to the coil from the ignition switch! With the gas turned off and the plugs out take one plug and ground it while someone kicks it over. You are looking for a white to blue spark. If you have spark, look into the carb while someone kicks it over (plugs still out) and look for fuel. If no go, start looking at the fuel supply and the intake. This is assuming your engine is in good shape.

    https://www.directparts.com/static/articles/shovelheadtiming.html
    CD, Sep 16, 2005
    #6
  8. hotroadking

    hotroadking Super Moderator Staff Member

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    I understand the fustration spent a week on a friends RK with a bad ignition, we had to re-wire the coil and put in a new Crane ignition. It had spark, fuel, so wheres the bang.

    As tough as it is to stand there and look at the bike, it's as tough to hear about and help over the net when you can't see or hear it so bear with the comments.

    1) Check compression, just for kicks it tells you the health of the cylinders.
    2) do a leak down test, pull the plugs and get the cylinder at TDC, have a buddy stand on the brake and use an air compressor to fill the cylinder. Make sure you're getting no leaks, - exhaust is exhaust valve, intake well you get the point.
    3) If those are good, then check spark, we found the timing was off 180 degrees so it was firing, but it wouldn't run, it was firing at the wrong time. Load up the carb with gas, no filter by twisting the heck out of the throttle and try and start- if it fires flames out the intake, timings off.
    4) Make sure timing is correct, get it at TDC and set the timing, won't hurt, might help.
    5) IF you have fuel, compression and spark, it should start and run, if it stops, then perhaps as been suggested a bad part (if you have a new part it doesn't mean it's not bad)
    6) check all the wires, check the battery ground everything can make a difference.

    Electrical problems are a b(tch.
    hotroadking, Sep 16, 2005
    #7
  9. Breeze

    Breeze New Member

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    Looses Spark

    CD may have hit on a good one. If you actually are loosing spark, check that capacitor. You mentioned that you changed points but didn't say anything about the capacitor. A bad one will give you grief.

    When you check wires for continuity, be sure you wiggle them to check for an internal break. If you just check for continuity without doing this you may think you have good wires when you have a problem.

    I've been on the side of the road for both reasons...
    Breeze, Sep 26, 2005
    #8
  10. Iron dog

    Iron dog New Member

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    I surpossed someone mentioned the suicide kill switch, mine broke on mine and gave me great havoc til one of my neighbors who don't even ride ask what taht does ,i said it will keep it from starting after short investigation my Hd was on the road!!
    Last edited: Oct 25, 2005
    Iron dog, Oct 25, 2005
    #9

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