Motor bogging under full throttle

Discussion in '2-Stroke Engines' started by ducky, Jul 6, 2007.

Tags: Add Tags
  1. ducky

    ducky Guest

    At idle speed I can gun it and it takes off well, but then I need to back off the throttle when I'm getting up to speed or it starts to bog, like it's getting too much fuel. At top speed I'm only giving it about 1/3 throttle, otherwise it sputters and slows down. I've leaned it right out, that's where it performs best, but it still seems to run rich. Any ideas?

  2. srdavo

    srdavo Active Member

    actually it sounds like it is running too lean. check for air leaks....intake gasket, carb,..etc. try a search on "engine bogging" here on this forum.
    keep us posted
  3. ducky

    ducky Guest

    Actually I tried richening the mixture up and it made it worse. That's why I figure it's getting too much fuel. But I will try to check for air leaks.

    Another problem is that it spits fuel out of the carb sometimes. Isn't it supposed to suck it the other way? :p
  4. azbill

    azbill Active Member

    I agree about the intake gasket, also check the carb is on far enought to seal to intake
    is your carb level ?
    could be the cause of it spitting
  5. rcjunkie

    rcjunkie Guest

    Run it at full throttle under load and shut off the fuel to the engine. Just before engine dies, it will do something. What it does should tell you if it is too rich or too lean. If it speeds up and runs better it is definitely too rich. If it does nothing, it was probably too lean to begin with.
  6. ducky

    ducky Guest

    It's running better now, running methyl hydrate and setting the mixture one notch richer has gotten me to scary speeds for a bicycle :evil:

    It still doesn't seem to want to make up its mind on the sweet spot. I have to feel around for it depending on hills/valleys. Thanks all for the input, I'll take some advice and keep you all posted :) It's fast enough, I just want it to be faster :p
  7. Bogging at WOT

    Hi if your bike runs fine all thru the power curve, and then, after running 1/4-1/2 block WOT it goes BLLLAAAAEEEHHH, and you back off throttle a bit and it picks right up, you need a new bigger "performance" jet.

    ohhh My, good golly, where would i get one ? NONE are made in China, and as near as I can figger, none will ever be. But, in a secret lab, in North Cali, in the dark, on a back street, on weekends and nights....... Someone makes them.

    WAT? you say? Yes, I am the guilty party..........

  8. iRide Customs

    iRide Customs Member

    LOL...give us more info Mike. Prices and availability.


  9. gone_fishin

    gone_fishin Guest

    please PM sellers for prices & such, or visit their sites...keeps actual commerce off the board that way, allowing us to maintain some impartiality...thanks 8)

    so...jetting...this has come up before. are you saying the flat-spot at around 19-21 mph (and again at top-end) on level ground indicates not enuff fuel?
  10. iRide Customs

    iRide Customs Member

    Will do Augie...sorry.

  11. gone_fishin

    gone_fishin Guest

    not a problem, dan...just using the situation to make a "public service" announcement :)

    so, mike...about my question on jetting...can you 'splain in terms even i can understand?
  12. Single speed jetting problems

    Hi Augi and gang. Well these engines were designed to run at multiple altitudes, and in a variety of temperatures, reliable, but not necessarily well.
    I typically have little to no starting problems with any of them. If you are not used to a full power band run from the engine it is a bit difficult to explain, but I'll try here tonite.
    Your plug, after a run at any given speed (except idle) When engine is shut down "mid run" should be a light chocolate milk brown, tho if at speed when killed may be a bit wet.
    Chalky white means lean anyd you'll soon be buying an engine. Black, wet, oily, means too rich (rare here unless you pull the needle up too high yourself.
    If your jet is a bit small (for most apps they are) you may not notice it's weakness in running till you do the extended WOT run and it says Blaaaaaeeeeehhh, and you back off throttle a bit, and she comes back alive.
    Remember, that high altitude requires SMALLER jets, and I'm tuning for seal level (where you northern "beach people" are, eh hoser???)
    !!!! ohhh I'm yusk kiddin, doon't git alarmed!!!
    Sooo, these engines were like "mid-range" jetted so they would run all over China.
    If you go Blllaaaeeehhh, and you are low altitude, I can tell you, that not only will you resolve the blaaaa, but that you will pick up mid-range power in a noticeable way. Merely rasing the needle does not actually accomplish the same thing, or we would not have made jets.

    The carbs for these engines are apparently all made in exactly the same factory, and are basicly identical.
    48, 55, 60, 70, so called 80 )69cc) all using the same carb, pipe, and main jet. This means they are no where near in tune. Ask any hot-rodder and you don't use the same carb and jets on a 283, as you do on a 427.

    Please ask more if I've not been clear, I got to head to bed, as I'm barganing for Seasonal employees, against (with?) the state of CA for benifits and money, and I'm beat, Mike