Home Forums 2-Cycle Racing My kt100 won't start.. Any ideas?

This topic contains 9 replies, has 4 voices, and was last updated by  tony zambos 6 months, 1 week ago.

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  • #66542

    Bob Spedding
    Participant

    Ok, so I can’t get my engine to start. It’s getting plenty of fuel and it’s getting plenty of spark.  I’ve even changed the spark plug to three different ones. The ignition  coil is new. It’s got plenty of compression.  When I pill the spark plug it appears dry.  When I pull off the air filter and try to start it and put my hand over it it gets a lot of fuel on my hand.

    What am I missing?

    Thanks

    #66548

    tony zambos
    Participant

    Bob,
    One of your assumptions must be wrong. What happened between the last time it ran and now? First, double check to see if the needles are open on the carb, a quarter turn open for the high speed needle and 1 1/2 on the low. If the carb has been apart, make sure the diaphragms are in right and the metering needle is not stuck.
    And is your starter turning the motor over at its normal speed?

    LAD Specialties / tony kart / rotax / kt100

    #66549

    tony zambos
    Participant

    Take a look at the pulse line from the crankcase to the carb.

    LAD Specialties / tony kart / rotax / kt100

    #66552

    Bob Spedding
    Participant

    Thanks. Nothing has changed since the last race ran good and has been in the garage since.  Fuel was drained after the race.  My low and high are adjusted as you say.  The carb has not been take end off and my starter has a full charge to it should be cranking at its maximum.

    Not sure what the pulse line is. I’ll have to look into that.

    Thanks!

    #66559

    tony zambos
    Participant

    Bob,
    There are two lines to the carb, one is the fuel line and the second, which probably is a smaller diameter, is the pulse line running from the crankcase to the carb. Make sure it doesn’t have any cracks or breaks and is tie-wrapped at both ends. The pulse line operates the fuel pump in the carb by transmitting the changes in air pressure that occur in the crankcase.
    If the plug was wet, you would expect that there wasn’t any spark. In your case, the plug is dry and I’m assuming you are not getting fuel into the cylinder. The best way to eliminate your carb is to borrow another one and try it on your engine. You also might want to remove one needle valve (H & L) and check if the tip of the valve has broken off. When was the last time you disassembled the carb and put a kit in it?

    LAD Specialties / tony kart / rotax / kt100

    #66566

    Bob Spedding
    Participant

    Thanks. OK so now I understand what a pulse line is 🙂  it is intact, no leaks and it is wire tied at. Otherwise ends. When I try to start the engine I can see that fuel is moving through it. Or at least it appears that way. I’ve pulled the needles and the look fine. The carb was pulled and about a month or so ago was repaired by my engine builder.  We’ve ran three races fine. I check the passage ways in the carb and they appear fine and I didn’t find any junk or anything.

    Thanks for the help. I’m baffled.

    #66578

    Bill Angel
    Participant

    Make sure the throttle is cracked open either with the idle screw or the foot pedal. It needs air and fuel.

     

    #66580

    FREDDY SANDOVAL
    Participant

    If you drained the fuel out of it, then you need to gravity bleed fuel till there is no air in the fuel line going to the carb.

    Once you have no air in the line hold the throttle open while cranking the engine, that sucker will start.

    Easiest way to get it started, turn the “T” handle (low needle)  almost 1/2 a turn close and then quickly open it up to 1 1/2 turns once it starts. That should work, especially when you already have good compression, good spark, and a good spark plug.

    #66588

    Bob Spedding
    Participant

    ok we got it figured out.  The rpm wire end was laying on the engine head causing the spark plug, even though it was showing current going through it, to work but not produce enough electric to ignite the fuel. Once we rewrapped it around  the ignition coil correctly, she fired right up. Craziest thing I ever seen.

    Thanks for all the help. I really appreciate it.

    #66652

    tony zambos
    Participant

    Bob,
    First of all, glad your engine is running. But, you said the RPM wire was laying on the head. I’m assuming that’s the high voltage cable to the spark plug rather than the RPM sensor wire running to the tach. There shouldn’t be any leakage out of the cable.

    LAD Specialties / tony kart / rotax / kt100

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