loss of power

Discussion in 'General Questions' started by rj1967, Jun 9, 2015.

  1. rj1967

    rj1967 Member

    Have an 80cc no name that I cant get over 15-20 mph. The needle is set on notch closet to point and idle screw is wide open. Im thinking maybe the float. Can someone tell how to set the float to get max power and speed? Thanks.

  2. darwin

    darwin Well-Known Member

    Try search RJ, that subject has been covered a 100 times. If not be patient someone will help ya out. I've never owned a happy motor so can't give you details.
  3. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    you don't say what kind of carb so I will assume you have an NT.

    The idle screw will have no effect on your top speed or how your motor runs.
    All the idle screw does is raise the slide by the rounded end engaging a ramp
    which is the same as twisting the throttle.

    Put the clip back in the middle or 1 up from the middle.

    Why is the clip on the lowest notch?
    This is richening a probably already too richly jetted carb which will make it slow.
    Is the motor 4 stroking at wide open throttle?

    Is the throttle cable opening the slide fully?

    You give no info, like is it a new build or what led up to this low speed?

    What altitude you are at, mods, gearing, etc.

    Post a pic and do not mess with the float level.
  4. rj1967

    rj1967 Member

    Not sure what you mean by 4 stroking..and somone suggested he last notch for more power. Not a new build..bought it used.
  5. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    The bottom notch will usually make less power.

    Did it ever run better?
  6. rj1967

    rj1967 Member

    Yeagh originally what I did was put cpl small holes in muffler cap..put needle on notch closest to point. Rand great. .and fast. But I didnt have an idle...tryed moving up a notch for idle...wound up flooding hell out of it. Moved it back down and adjust float a little.. runs better but not like it did. And still no idle. Lol. Thougt about buying an rt carb for better performance and speed.
  7. Slogger

    Slogger Member

    You should clean your float needle and seat and set the float height as close to original as you can.
    I think 21 mm between the edge of the float and the mating surface of the float bowl rings a bell. ?
    The jet should be more or less flush with the float when it's upside down in your hand, that would be close enough for government work.
    Somebody correct me if this is wrong.. it's been a while.
    The needle height controls the mixture from idle to 3/4 throttle. The higher on the needle you put the clip, the lower the needle drops into the hole and the leaner the mix.
    Putting the clip near the point is the richest groove. Most guys have theirs on the second notch down from the top.
    Mine ended up on the top notch. If it's too rich or lean at full throttle, you have to rejet it to fix it. At full throttle the needle is withdrawn and the jet is free to spray all it can.
    I have a Dellorto clone and it runs good but no faster than the old NT. I like the auto choke deal and its non-adjustable float. I don't like its tendency to be too rich at full throttle while running right at lower speeds. It's tricky to set up right. They all are.
  8. rj1967

    rj1967 Member

    Ok I wanna make sure I understand correctly. .for more speed I need to set the needle closer to the top notch..away from the point..right?
  9. Slogger

    Slogger Member

    Yes. If it is 4 stroking and burbling, raising the clip will lean it out, since that lets the needle lower into the jet passage and blocks more gas.
  10. rj1967

    rj1967 Member

    Ok thanks what I needed to know.
  11. Slogger

    Slogger Member

    No trouble at all.