uneven idle, rev, revving while idling, power cuts out on hills, How I fixed it!

Discussion in '2-Stroke Engines' started by Soundquist, Apr 29, 2014.

  1. Soundquist

    Soundquist New Member

    Hey all, no question here just a useful tip for anyone who might have this same problem. My bike seemed to rev wildly and die down and just fluctuate all over when it was idling. Sometimes the power would cut way back as I was speeding down the road. Scary, possibly dangerous and most of all annoying! I figured it was a fuel problem, I assumed it had to do with air bubbles in the gas line because my line is such that my fuel filter is not flowing "downhill" but has a bit of an upward angle.
    I looked around on the threads and found a similar problem, somebody suggested that the "float fork" in the carb was possibly the culprit, to disassemble and check fuel flow. I took the float bowl off and discovered the brass tube that goes though the "donut hole" of the float, through which the needle slides, was just hanging on by a thread, so to speak. I tightened it in all the way, it had almost a 1/4 of an inch to go, reassembled and bam! Nice smooth idle. It must have slowly unscrewed with vibration, this may be something to check during the original build. Make sure it's in there tight! Hope this helps somebody, I tried to make the title searchable for the symptoms.
     

  2. butre

    butre Well-Known Member

    my idle has been weird for the past few days, I attributed it to being an old dirty plug in my engine. I'll check that out next time I get some tools on my bike.
     
  3. Soundquist

    Soundquist New Member

    Yeah the plug mag be part of my problem too, seems a bit uneven when running. I've had the same old stock plug through a few different rebuilds and such for quite a while. I just ordered an NGK and hope it helps, I had also just gotten a generic expansion chamber before this problem really started happening, especially the trouble on hills. I read up on these and it seems they rob mid-range power for top speed performance, I've been running 16:1 forever, heard bumping that up can help, or extending the muffler at the base.
     
  4. butre

    butre Well-Known Member

    You should shorten the gearing when switching to an expansion chamber. It sounds counterintuitive but the extra top end power will let you use more of the rev range than you would have otherwise.
     
    Soundquist likes this.
  5. Soundquist

    Soundquist New Member

    Sorry, what does shortening the gearing mean? I assume more teeth on the rear sprocket?
     
  6. butre

    butre Well-Known Member

    you got it, more teeth on the rear
     
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