Brand new engine won't start =(

Discussion in '2 Stroke Bicycle Engines & Kits' started by Tomasito, May 3, 2011.

  1. Tomasito

    Tomasito New Member

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    Hi all, I installed a kit in my girlfriend's bike, but the little $#%&$ won't fire, i ride it like 15 times arround the block trying to start it up (with the whole family on the street waiting to see it come alive) and nothing, not a single explosion.

    This is what i've checked:

    · I have spark, (although i seen it a little weak, i don't know if this is common in these engines)
    · I have compression
    · Gas goes into the carb with no problem
    · Gas doesn't reach the cylinder i think. I rode it a lot and the spark plug is completly dry.

    I checked my throttle cable assembly and lowered the needle to the lower point just in case, and nothing, the spark plug comes out completly (and i mean not even smell) clean and dry.

    So I think it might be either the carburetor or the clutch slipping, what do you think?

    Please help me, i'm totally freaking out, the friday is my gf's birthday and this was my present for her, i'm very sad for her :(

    PS: I have a spare brand new kit in case I need a replacement, tomorrow I'll try a new carburetor, CDI and spark plug, just in case.

    Any advice? :(

    Thanks in advance.
     
  2. rohmell

    rohmell Active Member

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    Yes, try the other carburetor and see if you have the same situation.
    Also, check the magnet, it might be on backwards. With the flats at top and bottom and cylinder at TDC, the keyway should be at 1 'o clock.
     
  3. Al.Fisherman

    Al.Fisherman New Member

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    Magnetto pictures by Ron-Becker - Photobucket
     
  4. Tomasito

    Tomasito New Member

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    Thanks, I'll look into those things in a couple of hours.

    I'll keep you posted!
     
  5. Eric2.0

    Eric2.0 New Member

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    Welcome to the frustration and I know how you feel.

    I have a 67 year old dad just waiting for me to work some magic so his dream of riding a motorized bike on Sundays to the local diner, can come true.

    This thread may help... http://motorbicycling.com/showthread.php?t=32705

    It's been three days of my trying to get this started and all I get is a few hesitating pops...no start...nada.

    It's my understanding that these things are very temperamental and take some hardcore persuasion to get running. I saw many that just start though, of course mine won't.

    I've sealed up all the intake and all gaskets, car ect ect, Got a NGK plug, hardwired the wires, made sure the magneto is right...I did everything and I get nothing but being tired from pedal starting.

    It's very frustrating.
     
  6. rohmell

    rohmell Active Member

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    Eric,
    I feel bad about all the problems that you are having, and if I were closer to you, I would have been over there to help.
    Maybe get another engine, hopefully it will run the first time, then you could substitute parts from the bad engine until you find the SOB part causing your no run condition, then eff it up real bad.
    I have never met an engine that I could not get to run. If you keep trying and trying, until you solve the problem, then you will be able to say that, too.
     
  7. Tomasito

    Tomasito New Member

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    Well, as i supossed, the clutch was slipping, i adjusted the flower nut and it came to life.

    BUT, I had the carb needle in the lower (richer) setting so it ran like if it was choked. I changed the needle to the second slot from top and tested again.

    It didn't respond too well, the clutch was still slipping a bit, so i adjusted it again. I could take off at the first try, and even ran 3 or 4 blocks but the throttle didn't respond too well (as i accelerated it became choked).

    Now when i start the engine if i pull a little the throttle it chokes, and if I stop pedaling or put the clutch in it stops (i can't idle with the clutch disengaged).

    For me it seems that is way too rich, but the needle is in the second slot from top, do you think i must try setting it a slot up?

    The spark plug is new so it hasn't taken color yet (so i can't see if it's too rich from the color).

    I'll check the magnet too to see if the timming is wrong.

    Please let me know what do YOU think, thanks.
     
  8. rohmell

    rohmell Active Member

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    If you have started the engine and it is running, then magneto and CDI are OK.
    Concentrate your effort on the carburetor.
    Default position on the needle is 2nd from top.
    Maybe you need to rejet (solder shut and redrill)
     
  9. Tomasito

    Tomasito New Member

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    Well, i've tried changing the whole carburetor for a completly new one and it was exactly the same. I also tried the needle in 1st, 2nd and 4th from top, nothing, it chokes, can't idle and goes off after 5 seconds.

    I'm so paranoic about this.. This is a so simple engine and i can't get it to run. I'm not a newbie, i've serviced and repaired many engines but with this one i've no luck...

    I think i might have an air leak, i'll have to check in two days when i visit my gf again.
    In the meantime i'll try to think and come with something else for a solution...


    In other news, my girlfriend also wants to kill me every time I go with the moped, because I get in a really bad mood and don't pay attention at her. So i've to work fast when she doesn't sees me till she sees me and gets in bad mood in 5-10 minutes. .weld
     
  10. Eric2.0

    Eric2.0 New Member

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    Don't feel bad. I've built 358 Chevy dirt track engines, built my cousin's 250R engine, play around with Model airplane engines as well as a small jet turbine fo ra Radio Control helicopter.

    And this china engine has me stumped frustrated and pissed off lol

    Apparently it's normal for them to be hit or miss with no quality consistency at all.
     
  11. Tomasito

    Tomasito New Member

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    Yeah, is sooo frustrating that the simplest engine on earth can cause so much headache, and my gf wanting to kill me definetly doesn't help.

    It's almost 5am here and i'm still thinking on this engine...

    I forgot to say, that i've already tested two diferent new sparkplugs (gapped to 0.028 and 0.034).

    The friday i'll search for air-leaks in the manifold/carb, and change the cdi, just in case (the tiny spark bothers me, too weak for my taste). I already have a spare one, so it doesn't hurt to try...

    Also i live 25 miles away from my gf, so it isn't super easy to go there to try something in the bike.


    I'm now thinking on selling my other kit and buying a B&S for my next build, they're almost the same price...
     
  12. Tomasito

    Tomasito New Member

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    I forgot to put my results.

    That friday i changed the exhaust and the CDI. And also i sealed the manifold with high-temp silicone sealant.

    It worked right away.

    Now the only problem is that i've to have the choke like 1/3 closed for it to work right and that causes it to run too rich (oily sparkplug), but otherwise it carries me and my girlfriend (both in the same bike) just fine.

    PS: I did moved the needle clip a notch down and it helped a little.

    Me and my girlfriend are very very happy now that it works, and she now uses it everyday :D
     
  13. Eric2.0

    Eric2.0 New Member

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    Good.

    I'm about 2 seconds from slapping that junk out of the frame with a hammer.

    I'm dead serious.
     
  14. Tomasito

    Tomasito New Member

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    I was about to do the same thing, but with the hammer against the guy who sold me the kits. And that was serious too.

    Luckly, for the guy (and myself that i didn't got in jail haha), i could fix it.

    I really understand how you feel.

    Please post what's your problem ;)

    Cheers.
     
  15. Eric2.0

    Eric2.0 New Member

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    I'll show just how cheap these things are tomorrow,. At first swing with the 20 ounce claw hammer, it just punched a hole into the head lol. That is brittle.

    The carnage is disturbing lol....it won't be for all viewers.

    Bike is going to "recycle a bike" program we have here in town. It's already in the truck....lol...talk about walking away and quitting! .
     
  16. Tomasito

    Tomasito New Member

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    Ouch man >.<
     
  17. bugpilot

    bugpilot New Member

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    I have read your messages and they have brought me great comfort. I have just finished a new build and am having exact same problems. I bought a jet 70/80, two plugs, two carbs fresh fuel and not one pop. Is there a port on the intake side of the piston? I have run this thing downhill for !/2 an hour and the plug is bone dry, almost like the piston is in backwards. have you experienced any similar problems?
     
  18. crassius

    crassius Well-Known Member

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    if the plug is dry, then you're not getting fuel - check petcock, both filters and carb

    if taking the drain plug out of the carb gives a good flow of gas when you turn on the petcock, then all filters are OK and you only need to check that the needle didn't fall into the main jet because the "c" clip broke or the slide is not going to the bottom & stuff like that
     
  19. bugpilot

    bugpilot New Member

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    Have fuel in bowl, checked needle. No luck. Changed carbs, same thing, plug is bone dry. Engine turns over fine, put fuel in air cleaner{just a little} won't even pop. I have tried different fuel, two carbs, two carbs, sealed intakes w/ sealer,
    flushed manifold, cleaned plugbupkiss, rode down hill ,nada, notuhin, diddly squat. I have chainsaws, weed wackers, dirt bikes, never have I had this much trouble starting a stupid eng. Thanks for any help and imput.:-||
     
  20. crassius

    crassius Well-Known Member

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    without looking at it, I can't think of any good advice except that the plug should not be dry - did you try starting fluid?
     

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