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Thread: 45 Coil or Carb?

  1. #1
    Join Date
    Oct 2007
    Location
    North East Ohio
    Posts
    986

    45 Coil or Carb?

    Iím hoping this doesnít become project but Iím having a problem with my 45 that Iím hoping one of you more experienced wrenches can help me with.

    Background:
    The engine was rebuilt a few thousand miles ago and has performed perfectly until last summer when one morning I went to start it and it took six kicks to get started. It never has taken more than two kicks to start the engine. Once started, it idled fine and revved up strong but when I went to ride it, as soon as I shifted to second the bike started to pop and instantly lose power until I backed off the throttle, then it would barely idle without me closing the choke halfway. I got it home and removed the air cleaner to find fuel drooling from the carb body. The engine was still warm but refused to start again. I guessed it had something to do with the ignition and just pushed it into the corner and havenít looked at it until a few days ago.

    What Iíve done so far:
    This year before attempting to start the bike I began by checking the ignition system. I was getting an irregular spark at the plugs while opening and closing the pointís dozens of times. Removed the points and found they had some significant pitting and replaced them. That seemed to fix the irregular spark but I did notice that I wasnít getting a real crisp blue spark unless both plugs were grounded. That didnít concern me at the time because in use they would both be grounded.
    Hoping I had found the problem I attempted to start the bike for the first time this year without any luck. I kicked and kicked (because Iím stubborn) trying different choke and throttle locations with the timing always in the advanced position, but the engine wouldnít even try to start even though fuel was once again drooling from the carb. I figured if the fuel was drooling from the carb that I would find the plugs wet but that is not the case. The plugs were as dry as a bone. I went from frustrated to desperate as my leg tired and did something I always everyone not to do with a flat head and sprayed some ether into the carb and closed the choke all the way. I gave it a kick and it fired up but barely ran with me keeping the rpmís high and the choke completely closed. It was popping and sneezing but would keep running if you can call it that at high rpmís. Any attempt to open the choke even one click will result in the engine instantly dying quicker that I can close the choke back up even with the rpmís so high you would think that it wouldnít be possible.

    Now thinking that I must have a severe manifold leak I removed the M88 carb and pressure tested the manifold for leaks and found none. Since I had Liberty Motorcycle remachine the manifold and cut me some custom fit manifold inlets back during the rebuild that didnít surprise me.

    So that brings me to the carb but before I start tearing it apart I wanted to ask here if my problem may still be a weak coil? Iím starting to feel like Iím chasing my own tail here so please excuse the long post.
    -Steve

  2. #2
    Join Date
    Mar 2008
    Location
    Beautiful Northern NM
    Posts
    10,866

    Re: 45 Coil or Carb?

    Condenser is bad if the points are pitting..
    Friends help friends move,
    Real friends help friends move bodies!

  3. #3
    Join Date
    Oct 2007
    Location
    North East Ohio
    Posts
    986

    Re: 45 Coil or Carb?

    Robbie, it’s funny that you mention the condenser; could a condenser cause the ignition to have no spark at all? The reason I ask is because when I first started checking the ignition I pulled the plugs to check for spark while kicking the engine over and didn’t see any spark so pulled the timer cover to visually watch the points and found no spark there either. I used a dollar bill to clean between the points and that’s when I started to find the irregular spark when opening the points by hand.

    Something else I found while checking the ignition after replacing the points was that while checking the spark using a tool that resembles a spark plug that you put the wire on to and has an alligator clip to ground it, I found that I will get a massive spark from it when it is connected to the rear plug wire with the front wire grounded but only a click if the front wire is not grounded, also if I connect the tool to the front wire I only get a click from it even if the rear wire is grounded. I’ve removed both plug wires from the coil and checked them with an ohm meter and they are perfect so it puzzled me why the tool only gives a massive spark from the rear wire and not the front wire.
    Last edited by ohio-rider; 06-12-2017 at 11:33 AM.

  4. #4

    Re: 45 Coil or Carb?

    Step 1 replace points,plugs,condenser
    Step 2 replace coil

  5. #5
    Join Date
    Oct 2007
    Location
    North East Ohio
    Posts
    986

    Re: 45 Coil or Carb?

    I’ll start looking for another coil to try but while I’m looking I still can’t rule out the carb.

    Here’s another thing puzzling me. I removed the carb very carefully to keep it level because I was interested in how much fuel was in it. I only found about a shot glass of fuel between the fuel strainer and the bowel in it. How could the bowl be that low without the carb leaking fuel as soon as the petcock is opened? The fuel strainer is clear and fuel is flowing freely from the tank, but only drools fuel out of the carb after LOTS of kicking.
    Last edited by ohio-rider; 06-12-2017 at 12:01 PM.

  6. #6

    Re: 45 Coil or Carb?

    I only found about a shot glass of fuel between the fuel strainer and the bowel in it. How could the bowl be that low without the carb leaking fuel as soon as the petcock is opened?
    Crap in the fuel tank.
    Crap in the fuel line.
    Crap in the fuel strainer.
    Needle valve stuck, not working.
    Float stuck in bowl.
    Serious leak in float bowl

  7. #7
    Join Date
    Oct 2007
    Location
    North East Ohio
    Posts
    986

    Re: 45 Coil or Carb?

    You may be on to something concerning a stuck float. When I first removed the bowel and flipped it over to pour the small amount of fuel from the bowel into a glass, I noticed that the float did not flip down as it should until I gave it a small shack. I couldn’t get it to stick again for me after that first shack but I’ll give it a closer look today.

  8. #8

    Re: 45 Coil or Carb?

    Those repop coils will lose 1 cylinder & the other will give good spark....all of the ones I have replaced were doing that

  9. #9
    Join Date
    Aug 2013
    Location
    the Netherlands
    Posts
    483

    Re: 45 Coil or Carb?

    Do you have a bowl with a bleedscrew?
    If you'd remove the screw and open the gastap, is the flow constant and strong?

  10. #10

    Re: 45 Coil or Carb?

    Steve.....If you want to try one of those Japan 6 volt coils, I can send one up to you.

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