Home Forums Shifter Karts CR125 /w PWM carb bogging down in low RPMS.

This topic contains 5 replies, has 6 voices, and was last updated by  Matt Dixon 1 year ago.

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    brian heaton

    Got a 99 cr125 with a pump around fuel pump, and a PWM carb.  I haven’t driven it in about 3 months. Took her out today, and noticed, right after being push started, I have to slowly roll into the throttle or else it bogs down. This only happens at low RPMs hot and cold temps.

    I was messing with the knob on the carb, but forgot where it was set.  Which way should I turn the knob?

    Thank you


    Brad Alan

    I set mine between 22-26 clicks… I believe that there are a total of 51 clicks.

    Turn it all of the way in, then back out 22-26 clicks.

    I’m not sure if this will solve your problem though.

    Be sure that you don’t have the choke still on (i.e. push down the black button after you get it running).

    Another thing to check… is the pump taking the fuel back to the tank working properly?  i.e. is the engine getting flooded at low RMPs as the fuel is not getting pumped back into the tank properly?

    Hope this helps!


    J.C. Peterson

    Have you checked the condition of your reeds?


    Ben Lewis

    I’ve used both the PWK and PWM and I’ve noticed that the PWM is very sensitive to a fat pilot jet down low and I’ve experienced this too on occasion. Then it disappears after like 3-5K and rips. Does it get better or worse as the day gets hotter/colder?

    I’ve also had electrical problems give this symptom too. Check your connections and solder them so they have no change to wiggle.

    " Turd Ferguson is real and he will pass your a** "


    Robert Tifft

    I noticed I was having this issue this past weekend as well. I agree it may have something to do with the pilot circuit being rich, although it does sound like a lean bog. I’ve pretty much ruled out the main jet and needle since they’re common sizes and slightly on the rich side. The choke knob should only adjust idle, so I wouldn’t suspect that.


    Matt Dixon

    Put the air screw back where it was, that wont help.

    If it bogges then clears out go down 1 jet on the pilot.

    If it hesitates then takes off go up 1 jet on the pilot


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