4 stroking at cruise, is this normal?

Discussion in 'Motorized Bicycle Trouble Shooting' started by mobicon, Oct 1, 2016.

  1. mobicon

    mobicon New Member

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    Got my bike running reliably now. Seems to have decent power and a smooth steady sound when under load accelerating or climbing a hill.

    However it always starts 4 stroking when I'm in a steady state low load cruise on the straight and level. When I hit the throttle it smoothes right out and jumps to power, but then begins skipping again when the load drops off on cruise. This occurs at any speed under low load and constant speed.

    I tried leaning the mixture, but it only got worse.

    Is this normal? Is this wasting gas?
    Thx
     
  2. crassius

    crassius Well-Known Member

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    some folks think they are 'leaning the mixture' when they reduce the oil in their oil to gas ratio of their fuel

    usually, 'leaning the mixture' means reducing the fuel in the air to fuel ratio coming out of the carb

    try lowering the metering needle in the carb and lowering the float level too - if this helps, then you'll know where the problem is
     
  3. WECSOG

    WECSOG Member

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    What Crassius said. In fact if by "leaning the mixture" you mean reducing the amount of oil in the mix, you are actually making it run richer.
    And yes, 4-stroking at cruise does waste fuel. Fouls the plug, too.
     
  4. mobicon

    mobicon New Member

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    I leaned the fuel/air mixture with the jet needle, not the oil mix, and as I said, it did not help.
     
  5. crassius

    crassius Well-Known Member

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    needle is easy to go back if wrong, try all the way lean - float level is also easy to undo, so try that leaner too

    if you see no diff at all, it may be a flow problem with ports/exhaust, but a leaner main jet could still be tried
     
  6. ZipTie

    ZipTie Member

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    if you are running a NT carb...I've seen this only once, but you could pull your air cleaner off so you can check and see that the choke is opening all the way. Some NT carbs have a janky lever that is made in 2 pieces and if the lock nut is loose the choke stays partially closed with the choke lever all the way open.
     

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