Carby Added AF, now engine idles crazy fast.

Discussion in '2-Stroke Engines' started by steelfan41, Jul 18, 2011.

  1. steelfan41

    steelfan41 Member

    OK, here is my problem. I have a HT with stock carb. I had been running it w/o an Air Filter for a month. (Just got the bike and the stock Air Filter fell off on ride home.) I added a low profile air filter to it and now it idles at like WOT. I have tried different air/fuel mixture settings. Nothing seems to help. This is my first bike and experience with engine tinkering so please be as specific as possible in your answers. Thx in advance. :confused::confused::confused:
    Last edited: Jul 18, 2011

  2. HeadSmess

    HeadSmess Well-Known Member

    how exactly have you gone about fiddling with these air/fuel ratios? theres only one way on a stock carb and you didnt mention it...

    anyways. can you please say airfilter? i was halfway through your post before i realised what you meant. i am stoopid though...

    so...idles high now it has an airfilter? sounds like its leaned out something nasty to do that... now, putting an air filter on where there wasnt one at all would tend to richen the mix, so it isnt that :)

    so we move on to the three or four other options.

    1; an airleak between manifold and cylinder and/or carb.
    2; the slides in the carby round the wrong way...
    3; part of your filter element is interfering with the slide and stopping it from returning fully
    4; you might just need to clean your jet

    and 5; the float level in the bowls too low


    anything else? probably!
  3. motorpsycho

    motorpsycho Active Member

    well an air leak would definitly do that. Check for an air leak where the carb mounts to the intake manifold.
    I doubt that the airfilter is interferring with the slide because it would have to be half way into the carb for it to interfere.
    if you remove the new airfilter, does the engine run like it's supposed to?

    back your idle adjustment screw almost all the way out and try re-adjusting it.
    sometimes the scew can get hung up on the slide causing the slide to be open too far.
    did you take the top of the carb off and pull out the slide before or after you installed the airfilter?
    it's quite possible that you re-installed the slide wrong and it could be binding up inside the carb.
    check your throttle cable and make sure that it has a little slack...not too much tho.

    A lean mixture will cause a high idle, but it would have to be EXTREMELY lean for it to rev like it's at full throttle.(you did mix 2 cycle oil in the gas right?)
    If the float level in the bowl is too low, the engine would rev up and then die because there wouldn't be enough gas in the bowl.
    When an engine runs out of gas, it creates a lean condition causing it to rev up, and then die right away.
    It sounds like yours doesn't's just revving like mad all the time.

    Adding an airfilter(even a high flow one) will make the mixture slightly richer than with no airfilter at all, so i don't think the filter has anything to do with the problem. remove the filter and see if the engine still revs real high, and that will eliminate the filter.
    I'm thinking you have a problem with either the carb slide or you have a serious air leak.
    Last edited: Jul 19, 2011
  4. steelfan41

    steelfan41 Member

    I am feeling quit noobish. I went to adjust the air/flow mixture and realized the throttle cable had slid out of the (housing screw?) and was keeping the throttle open, simply put the throttle cable back where it belongs, going now to see if she runs great again. Hopefully this will be the end of this thread!
  5. motorpsycho

    motorpsycho Active Member
    at least it was something simple.
  6. Lazieboy

    Lazieboy Member

    Air leak

    My Extendo carb had a leake and it was causing a high rev.
  7. steelfan41

    steelfan41 Member

    Mother nature has been against me all day, intermittent t-storms. :icon_cry: