Running amazing, but too lean.

Discussion in 'Motorized Bicycle General Discussion' started by fischer550, Jul 20, 2014.

  1. fischer550

    fischer550 Member

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    So I was having 4 stroking issues at low rpm's and my motor was feeling sluggish. I am at 5,000 ft above sea level and using opti 2 at 100:1. I was running an nt carb with a .60 jet, and the needle set at the top (leanest) and these were my issues. My plug would always be black, with these settings.

    But then I tried something else.

    I got an NT speed carb and an HD lightning CDI. WOW

    For the speed carb, I put the same jet (.60) literally the same one as the nt, and did the same needle setting. I am not lying, the motor felt so good, there was no more 4 stroking and she just felt strong, and for once I was really enjoying the ride.

    Put in a new plug, and went on a 4 mile ride (which in my past experience is enough to get some color on the plug). I was going half-3/4 throttle most of the time, and at the end of the ride I rode about 10 secs WOT and then shut it down without letting her idle.

    Plug=white. not even the smallest trace of oil on this plug.

    Now I am going to do some jetting changes tomorrow, I am just looking for why this would happen with the same settings as the nt carb? Just curious and want to learn. Thank you!
     
    #1 fischer550, Jul 20, 2014
    Last edited: Jul 20, 2014
  2. rogergendron1

    rogergendron1 New Member

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    what other carb wre u running ?
     
  3. fischer550

    fischer550 Member

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    I switched from the NT to the NT SPEED, but kept the same jet and needle setting
     
  4. Goat Herder

    Goat Herder Gutter Rider

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    Some carbs can come with differant size atomisers.
     
  5. Goat Herder

    Goat Herder Gutter Rider

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    Needles, jets, slides the list goes on..
     
  6. crassius

    crassius Well-Known Member

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    also, engine condition changes too - this week I realized that I must have gotten to the 5 or 6 hundred mile mark as my idle began to misbehave - raised the needle one slot richer and it improved, raised another slot and it got good

    these engines go leaner as they run in, which is why I set them a bit rich when new for customers that don't really understand all this
     
  7. fischer550

    fischer550 Member

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    Update: Moved the clip to one slot richer. Started her up, now there is only the slightest bit of 4-stroking at barely any throttle, but other than that she still pulls hard and nice. Checked the plug (only half a mile riding) and there is definitely some color coming on it. I will make the jet a little bit bigger for safety, but I am pleased to report that I now have a bike that is awesome and is running very well!
     
  8. Davezilla

    Davezilla New Member

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    Glad to hear your setup is starting to work very well for you Fisher... Your engine should be pretty close to broken in by now and that also contributes a lot to how well it can run, but you can also fine tune it from here so the 4 stroking is either eliminated or at an rpm that the bike is rarely used in, but it sounds like you're really getting the idea on how to tune these little carbs so the rest is more fun riding and less time tuning... Good Job
     

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