Engine only ran once; about to give up!

Discussion in '2-Stroke Engines' started by KeelHauler, Sep 5, 2008.

  1. KeelHauler

    KeelHauler New Member

    Like I said in my intro post, I would like start off by thanking all of you for the wealth of knowledge that is here. Thanks to you all I decided to give the whole motorized bicycle thing a try. Originally I was looking to buy a moped but realized that it would be near impossible to find a good moped for less than $500, so I decided to build my own! I purchased a 50cc Chinese (HT) kit off of eBay for $100, and paired it with a Schwinn bike I got from Target. It took a few nights to get the bike all but together, but I finally got it running. And it felt great! I made sure to take it nice and easy since it was still being broken in, and rode it around for about 3 miles. After the ride I put it all away in my garage and hoped for many more enjoyable miles.

    Now is where the trouble starts.

    I came back to the bike a few hours later, and just could not get it started. After a few failed attempts, and a few too many pushes of the plunger, I noticed fuel was dripping out from the carb filter, so I just figured it was flooded and waited until the morning. The next morning, still nothing. Skip forward about a week, and I still couldn't get it running.

    I've replaced the spark plug with an NGK B6HS, replaced the boot with an NGK boot, and replaced the spark plug cable with some better wire from Napa. Bike still wouldn't start. If I pull the plug out of the head and pedal, I get a spark, although it seems to be weak. I've tested the plug with a range of gaps from .015 to .030, none seem to get a start.

    I've pulled off the clutch cover, readjusted the clutch cable. If I have the spark plug out I can see the cylinder moving when the clutch is released, and I can only assume it is when the spark plug is in.

    I've tested the magneto to see if there is a short, and there is not. I am also getting a charge from it when I pedal the bike. The wires coming from the magneto have a secure connection to the CDI.

    There is not and has never been a kill-switch installed, and the white wire from the magneto has been taped to prevent a short.

    The carb has been disassembled, and it is totally clean. I can see that the throttle cable is actually moving the plunger in the carb when I pull the screen/filter off, and have tried starting with all different combinations of throttle positions.

    I am running the fuel/oil ratio at 24:1 after having seen that recommended on this site. I installed an inline fuel filter rather than the piece of junk that came with the kit, and there are no air bubbles in the line like other people have had.

    I tried giving a spray of WD-40 into the cylinder before trying to start, still didn't start. Same when I tried a little ether in there. Even tried some RC car fuel. Nothing.

    Pulled the head, and the cylinder and piston still looked good. Pulled the exhaust, rings still looked new. Same with when I pulled the intake manifold. The only thing I noted when I pulled the head was that there was no head gasket. I don't see how this could cause it to not run now seeing as it ran fine before just as it is. I have also read elsewhere on this site that other members have been able to run without a gasket. Also, I can't hear any air leaking out of the head when I am trying to start the bike.

    It's been about 85 degrees or so outside when I am trying all of this, so it's not like the engine is cold.

    I've tried starting at all different speeds, with all different positions of both the clutch and the fuel air mixture. Nothing works.

    I'm sure I am getting compression, because if I am rolling the bike along and I let out the clutch, there is a noticeable drag on the bike.

    Well there you have it. I'm sorry it is such a long post, but I am at my wit's end trying to get this thing running again. I've done quite a bit of searching on here, and I believe I have tried just about everything I can.
    Last edited: Sep 5, 2008

  2. BSA

    BSA Guest

    Did your engine get wet at all? If so it may be the magneto.

  3. Mountainman

    Mountainman Active Member

    KeelHauler -- sorry to hear about - all that you have done and still not running.

    You mention that your motor came with no head gasket --
    had you done a compression test ?

    If not compression - probably elect...

    Happy Riding from - Mountainman
  4. Don't give up.It's just a Machine.:grin:

    Try giving your vender a call he or she will walk you thru Basic trouble shooting .
    If you start getting Frustrated and wish to speak to someone one on one Via Phone
    your welcome to give me a call, I've been know to have a bit of knowledge regarding
    these little Motors.
    I'm sure we can figure out your Problem and get you in the wind.




  5. s_beaudry

    s_beaudry Member

    Blue Collar Bob,

    Just wanted to compliment you on offering help to someone who did not buy from you. Respect for you...

    Very admirable gesture on your part!
  6. bluegoatwoods

    bluegoatwoods Well-Known Member

    Blue Collar Bob,
    That is a nice offer. And it doesn't sound like the poster has a vendor; he bought it off of e-bay. You might be the only one who can help him. Good luck.

    I'll be interested to learn just what's going wrong. It sounds as though the poster covered everything. The missing head gasket sounds strange. If I were gonna place a bet, I'd go with insufficient compression.

    Hope it all works out.
  7. jmccrury

    jmccrury Member

    Try checking the plug to make sure it is firing. My motor quit on my while riding and I tried everything I read on here but couldn't get it going. I checked the plug but couldn't see a spark so I replaced the magneto and cdi and it worked. (the cdi was the problem, I replaced the magneto first but it didn't fix it)
  8. Rain City

    Rain City Member

    Make sure the idle screw didnt get caught on your pantleg or something and go out of whack.
  9. B.K. Hosken

    B.K. Hosken Member

    I'm guessing ignition, so either magneto or CDI. If it won't fire with ether/starting fluid, then it doesn't have spark.
  10. astring

    astring Member

    I must say that I am impressed. You are offering support on another guys kit. That is really nice of you.
  11. Id put it all back together try another spark plug and order a new cdi unit If you still have a weak spark, if its weak out of the cylinder its going to be worse with it under compression. Please keep posting on progress.
  12. KeelHauler

    KeelHauler New Member

    Sorry for the lack of responses everyone, I ended up going out of town for the weekend.

    And to answer BSA's question, the bike has never gotten wet. I'd also like to thank BlueCollarBikes for his gracious offer of phone support even though I didn't purchase the bike from him.

    I did attempt to contact the seller (he is located near Los Angeles, and I actually picked up the kit from him rather than pay the $50 for shipping). So far I haven't heard back from him, but to be fair it was the weekend.

    I ended up buying a new CDI and head gasket from dax, and now I am just waiting to get them. Quick question though, does anyone know how long it usually takes to receive something from him? I saw on the site that the engine kits take up to 15 days to ship, but I wasn't sure if that was true for parts as well. I'll keep my fingers crossed that it isn't...
  13. jmccrury

    jmccrury Member

    I've ordered from Dax twice. The first time I received the parts in 3 days. The second time it took 9 days. So you should receive them fairly quick.
  14. KeelHauler

    KeelHauler New Member

    Well, the engine is running! And it wasn't my CDI, and it wasn't my head gasket either.

    I found this posting: http://www.motoredbikes.com/showthread.php?t=14967 and thought I'd check my bike to see if it was turning or not. Turns out it wasn't. So after a little tightening of the clutch, it is running great. I can really tell the difference with my new spark plug too, because it is actually idling this time whereas it couldn't before.
  15. Hey great to hear, thats good advice that ill add to my folder of tips and troubleshooting on my computer for future reference. Not sure how to tighten a clutch yet just got my kit today but it wont fit on the darn bike i bought off line lol...so im looking at another .

  16. Glade your up in the wind.