Anybody know anything about the magneto magnet

Discussion in 'Lighting and Electrical' started by Kletus, May 30, 2016.

  1. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    My engine is misfiring at mid range and high RPM's After adjusting the carb jet needle all the way up and all the way down in steps It only got worse so i returned it to the middle factory position and started looking at the magneto and CDI. The rotating magneto magnet only has magnetism on one side. One side will clasp a screwdriver bade hard to it and the other side has very little magnetism and wont hold the weight of the blade. Could this be the problem?
     
  2. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,163
    Likes Received:
    13
    Lets start with the basics... How new is the engine, & what gas/oil mix are you using???
     
  3. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    Engine is a brand new LOL,LOL,LOL gasbike GT80. Mixture is 32:1.
     
  4. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,343
    Likes Received:
    35
    a rare thing, but that could give a weaker than normal spark - as the rotor turns, each side adds power to the CDI for a single spark

    if this is your problem, you should see harder than normal starting and better running as speed increases

    gasbike *should* send you a new one if you explain it to them as you did here
     
  5. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    LOL, I called Gasbike and finally got through. I talked to some guy named Lorenzo. His main focus was to explain to me how they weren't responsible for diagnosis and how they had protected themselves with their terms of service. He did agree to send me a new magneto coil and magnet but did not want to listen to anything else I had to say about the problem. was really quite obnoxious and aggressive.
     
  6. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,163
    Likes Received:
    13
    Here's a few more questions...

    Describe how you mixed your 32:1 ratio?

    Did you shake the gas & oil thoroughly before pouring it into the bikes tank?

    What is your spark plug gap set at? (.025" is good)

    I ask these questions because the simple fact that the engine is running at all is a very good sign that it's not a ignition parts problem (& might possibly be a fuel, jetting or gap issue).


    Please post some pics of your setup. :)
     
    #6 Venice Motor Bikes, May 30, 2016
    Last edited: May 30, 2016
  7. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    I poured 4 oz. oil in the can went to the as station put in 1/2 gallon shook the can and finished putting 1 gallon total in the can. and shook it again. Thought it might be the gas but it runs ok in my string trimmer. All 5 plugs gapped at.025". Engine idles well and has strong power on start up then as RPM's increase it starts misfiring and fouls the plug. I see no evidence of head gasket or base gasket leaks. My thoughts were it was running to rich or misfiring and loading the plug up. Lowering or raising the carb jet needle made it run worse so I concluded it must be an ignition problem. If the magnet doesn't fix it my next step is to cut the cdi box from the coil and wire the ignition coil straight to the magneto. If none of this works I will order a new coil and carb from Ebay. Only problem is the wait time and I'm ready to roll now and this thing misfires so bad its embarrassing to ride it down the street.
     
    #7 Kletus, May 30, 2016
    Last edited: May 30, 2016
  8. mogollonmonster

    Joined:
    Aug 26, 2015
    Messages:
    472
    Likes Received:
    3
    I would be willing to bet your main jet is too rich. This is normal. Break in your motor, then rejet. I'm with Venice on this one. My money says jetting.
     
  9. MEASURE TWICE

    MEASURE TWICE Active Member

    Joined:
    Jul 13, 2010
    Messages:
    2,031
    Likes Received:
    10
    I know the title of this thread has not really gotten any answer unless I missed something. What I mean is although I have a Briggs 4 stroke, the Magnet is only on one side of the flywheel on it. The other side is just a mass of metal weight to balance out the flywheel. I expect these engines might be the same. Some one using these engine and have it running good would probably find that one side is a magnet an the other side is not also.

    The other information that is being offered aside to help I know probably less of so see what you can find help on Carb and CDI.

    MT
     
  10. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    784
    Likes Received:
    1
    It is most definitely too rich. The needle does not do anything for upper rpm. It's only for partial throttle transition. If it's misfiring and sounds like a machine gun at high rpm, it's doing what's called 4 stroking. You can either buy a jet kit, or drill your own. A soldering iron and elecrical solder will work to close the jet, then a set of micro bits (size 60-81) can re size it properly.
     
  11. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,343
    Likes Received:
    35
    not sure here what is meant by 'coil' - do you have the super rat style ignition built as a unit inside the mag cover, or external CDI unit?

    with external CDI, the only coil is in the stator and CDI can not be eliminated
     
  12. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    The carb is a Keihin Carburetor Clone. I removed the main jet and #71 drill bit dropped through the hole, #70 drill bit would not fit so I assume it is .026 hole diameter. Humm, where to start. I also noticed that the brass tube that screws into the carb body that the main jet screws into was only finger tight.
     
  13. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    784
    Likes Received:
    1
    That's called the emulsion tube. It should be snug, not over tightened.

    Solder the jet hole shut first. The easiest way is with a plumber's torch. Clean the jet as well as you can, then with a pair of needle nose pliers, heat the jet slowly. Apply a couple seconds of heat, pull the jet out of the flame, try melting solder to the jet. If it didn't melt, reapply a couple more seconds of heat. You will not want to use very much solder. Just enough to fill the hole. Apply from the bottom (the bottom, as it sits in the carb, don't solder upside down lol). Don't apply too much heat. You don't want to melt the jet.

    I actually had luck with chucking the micro bit in a drill, but it's recommended to use a pin vise and drill by hand. Do not exert much pressure. You dont want to snap a bit. Once drilled, make sure you get all the shavings out, then reassemble it and go for a test ride. Continue until you get good power. Once it stops sputtering and 4 stroking, don't go any smaller. You want the jet as large as possible without affecting the performance. Too lean and you'll burn up the cylinder. Start with a 72 first, then work down.

    Once you get it dialed in, change the spark plug (gapped at 0.025", and go for another ride. You may need to re-jet after changing the plug.
     
  14. Kletus

    Kletus Member

    Joined:
    Apr 15, 2016
    Messages:
    117
    Likes Received:
    2
    A much appreciated thank you to all who replied to this thread. Its raining right now so I can't do much of anything. When I'm finished I'll post a reply as to how it turned out.

    Best regards
     
  15. mogollonmonster

    Joined:
    Aug 26, 2015
    Messages:
    472
    Likes Received:
    3
    Rainy days are perfect for shop work!

    While I'm not familiar with your carb, I can say that if your emulsion tube is loose, it can attribute to your problem. Agreen gave good advice all around for sure.

    Tinker and tune, tinker and tune. Before you know it, you could be like me... "Why spend all that money on a beat down used truck? For half a years insurance, I can build a NEW bike, that will do all I need."
     
  16. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,343
    Likes Received:
    35
    before I got a pin vise, I used to chuck the jet into the drill press and offer in the bit held in needle nose pliers
     
  17. Agreen

    Agreen Member

    Joined:
    Feb 10, 2013
    Messages:
    784
    Likes Received:
    1
    I wonder if the emulsion tube was finger tight and sealing, or loose enough to cause problems. Sucking in air from above the fuel level, or was the level high enough to suck extra fuel around the threads?
     
  18. Scooby225fre

    Scooby225fre New Member

    Joined:
    Jun 6, 2016
    Messages:
    7
    Likes Received:
    0
    Can anybody tell me in which position should the magnet be when its on tdc and if the magneto is supposed to be firing when the semi circle part of the magnet is straight up and down or the cut out section of the magnet is straight up and down. I'd appreciate any info. Cheers
     
  19. crassius

    crassius Well-Known Member

    Joined:
    Sep 30, 2012
    Messages:
    3,343
    Likes Received:
    35
    look around the board here - somewhere I have posts with pics of how to make timing mark and other CDI/mag info
     
  20. Scooby225fre

    Scooby225fre New Member

    Joined:
    Jun 6, 2016
    Messages:
    7
    Likes Received:
    0
    OK cool. I'll have a look for it and let you know how it went. Thanx for that.
     

Share This Page