Engine Trouble engine starts but bike doesnt take off

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

  1. lewsidius

    lewsidius Member

    hello everyone
    sorry if im posting something already up
    i just dont understand the lingo
    engine starts but bike doesnt take off
    i move the throttle open and no change in sound
    and i slowly come to a hault and the engine turns off
    the engine has a good sound and a consistent rythum

    so i dont know what to adjust or whats wrong????

    what does idle mean , is it when the engine is on or when it takes off

    any idea would be very helpful

  2. BoltsMissing

    BoltsMissing Active Member

    When you start a motor car, it's in Park or Neutral, foot off the accelerator and the engine is ticking over, that's Idling.

    By the sounds of it, you may consider asking a mechanically minded friend to oversee what you want to do with your bike. Not to get your friend to do it for your, but YOU get YOUR hands a little dirty and get a feel of what it's all about.
    Reading is one thing, it's just that, knowledge.
    But practical experience is another thing.

    Post some pictures of the current location of the problem you are working on, or post some pictures of the bike, so we can see what's going on.
  3. lewsidius

    lewsidius Member

    thanks for the reply
    good tips!
    i was also wondering how to check if im getting a good spark?
    do i take the plug out and keep the cap on
    do i take the cap off and see sparks
    i think the sparks come from the bottom of the plug, no?
  4. motorpsycho

    motorpsycho Active Member

    Oh boy!!!
    Ok, you could have several things wrong, but you need to know how to explain exactly what's going on.
    If you do not know what "idling" is, how can you explain what the engine is (or isn't) doing? The best way to learn is to try and descibe the problem, include pics or a video if possible, learn the right words for what part is what. Please try to understand that it's difficult for someone to try and troubleshoot the problem based off of what you are saying and that sometimes what people say doesn;t make sens if the right words or terminology isn't used.
    If you do not have a pull start on your engine and you are able to peddle start it (peddle bike to speed, let out clutch and the engine starts) then that tells me that your clutch is adjusted right.
    Now, if you give it throttle(twist the gas) and the engine does not rev up at all, then you probably have the slide installed in the carb wrong. The slide is the little barrel shaped peice inside the carb, under the top cap that the throttle cable hooks to and slides up & down when you twist the throttle.
    The slide can go into the carb 2 different ways, but only one way is correct.

    If you pull the slide out of the carb (by unscrewing the cap on top of the carb and pulling it out) the slide will be attached by the throttle cable. the cap, slide, needle, cable and spring will come out all as one peice. There is no need to disconnect the cable or anything else from this assembly
    Now, look at the slide itself closely and you should see that it will have 2 notches in it at the bottom (a long slot and a short slot).
    You need to put the slide back in the carb so that the short slot is to the left side (while sitting on the bike looking down at the carb) and the long slot should be on the right.
    The long slot has to line up with a little tiny pin that is cast into the inside of the carb. and the short slot has to line up with the idle adjustment screw.
    Slide the slide back into the carb and concentrate on getting the long slot to line up with the little pin. You can turn the slide as you lower it until you feel the slot find the pin. Also make sure that the needle is in the center of the carb (that's where the main jet is). The slide should go back into the carb easily with very little resistance. It should be a precise fit, but you should still be able to slide the slide up & down easily. All you need to do is get the long slot lined up with the little pin and the idle adjustmet screw will automatically line up with the short slot.
    now, put tighten the cap on top of the carb by hand...do not use pliers or anything like that because you can distort the carb body and/or strip the threads.
    start the engine and adjust your idle screw. (The little screw with the spring around it on the outside of the carb on the left side. Screw it in to raise the idle, and screw it out to lower the idle.) Set it to where the engine is ticking over nicely and not revving too high. You want the engine to sit there and run on it's own at a fairly low r.p.m. "pop-pop-pop-pop"
    If you have the slide in wrong, you will not have any throttle response (engine will not rev up when you twist the throttle) or the engine will be stuck at wide open throttle all the time and revving like crazy.
    I am assuming that you originally put the slide in the carb because the older n.t carb versions came with the carb partially unassembled. you had to hook up the throttle cable to the slide and then put the slide, spring, and needle in the carb and tighten the top cap.

    from what you are describing it sure sounds like you have the slide in wrong.
    or, you have way too much slack in your throttle cable.

    The best way to learn about this stuff is to ask questions, and then tackle fixing the problem yourself.
    IF you put the slide in the carb wrong, don't worry this is a very common mistake, and a very simple fix.

    to check if you are getting spark....remove the spark plug from the engine. Snap the spark plug wire back onto the top of the spark plug and rest the spark plug on the top of the engine (the cylinder head). now, turn the rear wheel with the clutch engaged (so the engine turns over) and watch the tip (the electrode) of the spark plug (the end that goes into the engine). you should see a nice blue-ish white spark but it will not be constant...it will be on-off-on-off-on-off.
    It will be a small spark and sometimes it's hard to see if you don't know exactly what to look for. But, sometimes you will hear it go "snap-snap-snap".
    If your engine starts and runs, there really is no need to check for spark. you either have spark or you don't and the engine won't run without it.
    BUT in some instances you could have a very weak spark that looks good, but is not strong enough to make the engine run.
    Last edited: Jul 18, 2011
  5. lewsidius

    lewsidius Member

    thanks alot that very insiteful

    i do understand what your saying:goofy:

    i just had a few dumb questions on stuff i was confused about :dunce:

    but that caught me right up and clarified

    some other forum postings kinda sent me off course a little cause of the way things were worded
    im gonna try the bike again first thing in the morning
    just wanted to drop a line and let you know your help is truly appressiated and your making a newb advance in knowledge
  6. lewsidius

    lewsidius Member

    Okay so i tried the bike before work after tightening the Throttle and the same thing happens. the bike idles then as i lose speed the engine gets quiter and i slowly come to a hault. the throttle is preety tight there is no slack there and when i turn it no noise difference. could it be i just need a bigger hill and turn the engine for a longer time period? im off to work but on return im goin to take apart the carb and see whats goin on. but its more then likely a carb problem. could it be the float? and that the engine is not getting enogh gas throgh the line?
  7. motorpsycho

    motorpsycho Active Member

    If you twist the throttl and the engine does not react at all to it, I will bet that you have the slide installed wrong in the carb.
    No, a bigger hill will not do anything for you.
    Once the engine is running you should be able to twist the throttle and the engine should rev up (just like if you push the gas pedal on a car while in park)
    The float really has nothing to do with how the engine revs up.....I am going to almost gurantee you that the slide is installed in the carb wrong.
  8. lewsidius

    lewsidius Member

    so i took apart the carb and the slide is moving proper back and forth
    but i noticed the tickler button was busted so i tried fixing it but it was too weak and snapped in half
    should i just fill it with a screw for now to seal it
    thats what someone did on another forum
    but the throttle has no slack and moves with ease and the spark plug definatly has a strong spark (ouch)
    thanks again :grin5:
  9. lewsidius

    lewsidius Member

    hello again
    i adjusted the float
    and gas is leaking
    but i started the bike anyway
    and it actually moved
    its stupid i know
    but i was able to go pretty fast
    and i wanted to see if it worked and it did
    however it really over heated

    but its helped me establish that there is a shortage of gas going in

    it either barely gets enough gas and just idles
    or it gets too much gas and doesn't idle but it takes off and overheats

    and i only move the forks on the float ever so slightly to make this transition

    when i look at the gas line when there is not enough gas it fills just to the bottom of the filter on the line

    and when its overflowing
    that when the entire line is full

    im so close
  10. HeadSmess

    HeadSmess Well-Known Member

    by the sounds of previous posts i reckon you think "over heating" is being slightly over 50 degrees celcius...

    overheating is when the engine gets to around 350 degrees celcius, the plugs melting, the pistons about to blow a hole in itself, and the **** thing has siezed! and you gotta be running it really lean to do that!

    ive never really had a fuel filter fill up completely. theres always an air bubble somewhere.

    unfortunately, everyone has written huge replies for you, explaining so much...and youre not having any luck.

    my recomendations? find a local, friendly mower mechanic and pay him for some hands on lessons! thats all the help anyone can give you now...sorry :)

    i reckon your needles not on the slide :D
    Last edited: Jul 20, 2011
  11. lewsidius

    lewsidius Member

    i realize that alot of people have been helping me
    and its alot of help, work and patients
    im not ungrateful and i appresiate it
    and im soo close to tackling this problem
    i need this to get to work otherwise i run it with out the motor powered on
    which isnt fun
    besides some people may have a similar problem and this thread can help them
    im learning so much and im not gonna give up
    im far tooo close
  12. motorpsycho

    motorpsycho Active Member

    The reason why gas is leaking is because you set the float level too low. the bowl is filling up with fuel and the tangs on the float can't fully close the needle and seat.
    The carb is flooding over, which is a bad thing.
    I kind of think that you don't have the carb assembled right or you have something way out of adjustment.
    A fuel line and filter usually does not fill completely up with gas, there usually is a small air pocket in there, and that's 100% fine.
    I think you just need to learn how to adjust everything, and you need to know how everything gets put back together the correct way.
    You should not be having this many problems unless you totally messed the carb up or installed it wrong (i have seen people install carbs sideways and they wonder why they don't work right).
    The bad thing about all of this is that incorrect installation / assembly. leads the builder to think that these kits are garbage. Then they get all mad and trash every company that makes these engines. Sometimes it all boils down to how the engine was installed on the bike, how everything was tuned and tweaked, and how much mechanical knowledge the builder has.
    If you slap one no a bike and get it running right away, you'll think it's great.
    If you put one on a bike and it takes you awhile to get it running due to incorrect wiring, faulty connections, carb assembled wrong, etc, you'll think it's a pile of junk.
    If you ever ride a m.b. that has been built correctly and properly tuned, you'd be blown away at how well they ride and how well the engines actually run.
    Last edited: Jul 21, 2011
  13. lewsidius

    lewsidius Member

    you should change your name to motophysic

    you were band on about the carb being sideways
    holy \&%^ how could i be so foolish
    its because it barely fit the other way
    and a month ago i didnt think it would matter
    but here i stand corrected
    any ways it runs now
    but it doesnt idle still
    it just takes off!
    im not sure what to do
    i have tried different settings on the float
    and i have tinkered with the idle screw and the throttle
    and i get the same results
    speed and lots of it
    but no slowing down or idling
    i think its still to lean
    just not sure how to correct it!
    and man its hot out side:sweatdrop:
    thanks again
  14. HeadSmess

    HeadSmess Well-Known Member

    its peeing rain here and im only hot n sweaty cus of my super sexy fireplace :)

    ha ha ha! sideways carbs!...ok, thats that bit fixed. oops he says.

    so now, it doesnt idle! back to the beginning!

    pull the slide out. the slot down the side, where the cable goes, should be on the side AWAY from the idle screw. theres a tiny lil brass pin down in the slide hole that keeps it lined up.

    OR the slide has a slight angle (cutaway) at the bottom. this should point away from the engine, or towards the airfilter. that, surprisingly, is part of the mix control. dont try filing it unless you know whats what though!


    thats a pretty good page there for the basics ;)

    though the HT carb is even more basic...all it has is a slide and a needle&jet. the only way to change the main mix is by drilling/replacing the jet. and the needle position effects mid throttle. there is no pilot/idle circuit...besides that cutaway in the slide...

    and checking if its too lean is simple. remove spark plug. if its white or grey, its too lean.
  15. lewsidius

    lewsidius Member

    thanks for the tip
    im gonna carefully look over the link
    it looks great!
    thanks again
    ill let you know of any progress
    man o man my bike gets hot
    i only ride it for a few blocks after tinkering!
    but i got a nice burn
    any ways thanks again
  16. motorpsycho

    motorpsycho Active Member

    of corse your engine is going to get hot.
    It's air cooled and they run hotter than a liquid cooled engine.
    you need to be moving to have air flowing over the fins to cool it off.
    sittting still with it idling for a long time is a bad idea.
  17. lewsidius

    lewsidius Member

    what up!
    i still cant idle so thats not the issue with the over heating
    but i imagine thats a problem
    when you idle with your bike ever does it idle with out holding the break?
    i heat up soo much very quickly and it gets sooo hot that i starts almost melting the boot on the spark plug
    i looked at a good tutorial about carburators and im gonna to adjust the needle setting
  18. lewsidius

    lewsidius Member

  19. motorpsycho

    motorpsycho Active Member

    heck yeah mine can idle without holding the brake (but i don't have a centrifugal clutch on my bike and i'm not sure if yours does or not).
    Man if your engine is getting that hot, there's definitly a problem. I'll bet that it's running way too lean and that can burn up the piston.
    you do put oil in the gas right?
    running a 2 stroke on straight gas will make it run extremely hot and it will kill the motor in no time.
  20. lewsidius

    lewsidius Member

    thanks alot man
    it was very lean so i adjusted the needle settings
    and it doesnt get as hot
    it was kinda smoking from the muffler alot
    i took it for a spin and it runs alot better
    and doesnt seem as hot
    and no more smoke
    i just need to drill a small hole in the cap to fix the gas issue
    every once in a while
    i have to unscrew the cap
    or the bike will stop
    and even my kill switch works!
    when you squeeze the clutch it makes a weird sound and stars mis behaving
    is that normal?
    thanks again