erratic running of engine

Discussion in '2-Stroke Engines' started by geronimo, May 28, 2010.

  1. geronimo

    geronimo New Member

    Beginning on second gallon of break-in gas. The engine just began cutting out then quit. I rewired the kill switch thinking I was robbing the magneto, on the "white" wire. It didn't seem to help. I also moved the c-clip up on the throttle valve.. I am getting frustated. can anybody diagose? the problem> THANKS

  2. geronimo

    geronimo New Member

    There seems to be something intermittent----,gas, or the electrical i am stumped as to what it could be. I cannot visually spot the problem. It takes off ---then stops---off and on.
  3. Vistaman73

    Vistaman73 Member

    what ratio you running? check your plug, if its black, gooey, than your too rich. if its white or gray, then your too lean, you want a dark tan, chocolate color. 32:1 is what i run. make sure everything is on right and check to see if your idle speed is correct. do all that and then check back. BTW: vids always help. ;)
  4. GearNut

    GearNut Active Member

    Are you using the factory electrical connectors?
    They are notoriously horrible.
    You are better off soldering the connections or using balun spade connectors.
    Here's a picture of a female connector as sold at O'Riley auto parts:
    And here's a male connector:
    Most all auto parts stores sell them in the electrical section fairly cheap.
    I recommend crimping and soldering them on, and using heat shrink tubing to insulate them.!s!tubing
    Last edited: May 28, 2010
  5. AussieSteve

    AussieSteve Active Member

    Vistaman73, the terms 'rich' and 'lean' do not refer to the fuel/oil ratio. They refer to the fuel/air mixture. It's very confusing when you use those terms for the fuel/oil ratio.

    Secondly, you don't vary the amount of oil to achieve the correct plug colour. This is bad advice.
    If the plug is black, the fuel/air mixture is too rich. If the plug is white or grey, it's too lean. The plug should be light tan. For low to mid-throttle openings, the slide needle controls the mixture. At WOT, the main jet comes into play.
    Further, setting the idle screw correctly will have no bearing on this problem.

    geronimo, as Gearnut says, double-check all electrical connections and make especially sure that nothing is shorting to ground.
    Sometimes the HT lead can be a bit loose in the CDI and plug boot. Ensure that it's screwed well into both.

    Have you tried a new spark plug? If not, do so. An NGK B6HS works best.
    Also, check that you're getting adequate fuel flow from the tank. Do you have an inline filter?
    If I were you I'd also pull the carb apart and give it a clean.
  6. Vistaman73

    Vistaman73 Member

    Aussie, your right. My post was a little confusing. I was jumping around giving advice on what COULD be the problem.

    1. What's your ratio? Again, 32:1 is a good one
    2. Check the plug for a tan, chocolate color. Black is too rich. White/grey is too lean.
    Use the clip in the carb to adjust for that, I can't remember right off the top which way is richer/leaner. Sorry.
    3.And since the description was not the most detailed, I just threw the idle speed in there. It never hurts to check Aussie. :) Make sure its still there and set right.
    4. Check the fuel lines and carb/petcock for blocks. Clean the carb and install a fuel filter.
    5. Check connections and get a new plug, or even get a new cdi/connections.
    6. If you can, check the magento to make sure it is working right.

    There, that is what I was trying to say, and I added a little bit. Aussie, thanks for stepping up and telling me, I'm glad you did. It's nice to get a respectful post back to me for once. :) Hope this all works out geronimo.
  7. AussieSteve

    AussieSteve Active Member

    Vistaman73, I'm glad that you didn't take personal offense - none was intended.

    To enrich the mixture for low to mid throttle openings, the slide needle needs to be raised, allowing more fuel into the mixture. ie The clip must be lowered.
    And vice versa.

    For full throttle, the main jet size comes into play. A larger main jet will enrich the mixture and a smaller one will make it leaner.

    There's a bit more info here:- NT Carb Tuning Basics

    Incidentally, I ran mine in with a 16:1 fuel/oil ratio, then changed to 20:1, which I still use today. If the carb is correctly tuned, there's no build-up on the plug and it's a nice tan colour. (There's a pic of my plug colour in the NT Carb Tuning thread.)
    With these engines, due to poor manufacturing tolerances, the more oil you can get away with, the better. It helps the piston rings seal against the cylinder wall, ensuring maximum compression.
    Last edited: May 29, 2010