My first ride... No joy.

Discussion in 'Motorized Cruiser Bicycles' started by Dymaxion, Jan 3, 2010.

  1. Dymaxion

    Dymaxion New Member

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    Had some time off over the last week so I spent a few evenings getting my first motor bike together. Bike is a walmart schwinn del-ray, and the engine is a grubee skyhawk 66cc slant head.

    Tonight I finished it up and had to immediatly try it out (in 10 degree weather after dark). Got up a good head of steam, started down a long hill, big smile and lots of excitement as I engage the clutch, and.... Nothing. The piston is pumping away like crazy but she just wont fire. So I peddle back up the steep hill (why didnt I get a bike with gears?) and try again. Same thing. One more time up the hill (did I mention 10 degrees outside), and... Nothing. By now I am sweating, freezing, and a little miffed.

    I checked all connections and everything looks good. Pulled the plug and it is damp so it is getting fuel. I rode along and held the plug to the cylinder wall and saw spark. I had some other family matters to attend to this evening so it will have to wait until tomorrow after work to try again.

    Here is my 6-step plan for tomorrow - let me know if I missed anything or you have any other suggestions:
    1) Put in new plug gapped to 0.025"
    2) Completely disconnect the kill switch wires and wrap up the white wire in tape so it can touch anything (don't think this is it since I saw spark, but cant hurt)
    3) Drain out gas which is 18:1 per instructions
    4) Shut off fuel valve and run a bit with the clutch engaged to empty out the chamber
    5) Refuel mixed 24:1
    6) Cross fingers, say a prayer, charge down the hill and pop that clutch.

    Thanks all!
     
    #1 Dymaxion, Jan 3, 2010
    Last edited: Jan 3, 2010
  2. MatCauthon137

    MatCauthon137 New Member

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    ok, admittedly, i also just finished building my first bike, but have had no problems with it. mine is a 48cc grubee skyhawk, but i think all grubees are the same, and having a previous motorcycle i just have a couple of questions for you that you probably already thought of, but, on mine (up here in the cold mountain air) using the choke to start it is a must, so you did engage the choke, right? also, there is a tickle button on the left side of the engine that is used to prime the engine after turning on the fuel line but before trying to start. that is the only thing i can think of. i wish you luck :-||
     
  3. Dymaxion

    Dymaxion New Member

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    Good ideas - yes I was using the choke, and yes I primed it first. In fact, I could hear a little sloshing in the bowl when I pressed the tickle button.

     
    #3 Dymaxion, Jan 3, 2010
    Last edited: Jan 3, 2010
  4. Dan

    Dan Staff
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    Bummer Dy. They can be maddening. Seems like you have a handle on it and will get her going. Please keep posting. Fuel, spark and air. Really dunno, bit of a stumper.
     
  5. saetta

    saetta New Member

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    I had a similar experience on one of my builds. For me the kill switch was not truly grounded. I am sure you will figure yours out. Good luck and enjoy!
     
  6. biken stins

    biken stins New Member

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    got spark ? check wire to CDI.
    Someone sugested warming cylinder with hair dryer.
    Good luck.
     
  7. Dymaxion

    Dymaxion New Member

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    I am getting spark so I believe I am ok there. During the build I did replace the plug wire and boot with a solid core copper wire since I needed an extra inch of length. I guess it is possible there is a bad connection in there somewhere and I am getting a weak spark. Not really sure how to tell if enough juice is getting to the plug.
     
  8. Nougat

    Nougat New Member

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    Check spark with the plug out, and out of the sunlight, the spark should be fat and bright blue across the electrodes. Skinny yellow spark is yucky.
     
  9. XFired

    XFired New Member

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    Here's my thought,crack the throttle 1/4 turn when trying to start, the carburetor slide may be too low in the carb,basically choking the fuel supply off...let us know...
     
  10. 2manyprojects

    2manyprojects New Member

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    I have the same issue with mine, exact same motor, I have spark outside the head, but none when trying to start, double checked everything, even had help from Jim at SBP and he was just as stumped as I was. I would love to figure out the issue, and if i do, i will let you know
     
  11. Dymaxion

    Dymaxion New Member

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    Got It Running!

    dance1 Got it running!!!

    Not entirely sure what fixed it, but here is what I did tonight. Got out a new plug, gapped it and set it aside. Drained out the fuel from the tank and bowl drain, shut off the fuel valves and reloaded the tank with fresh gas mixed at 24:1 this time. Then I completely disconnected the kill switch and wrapped up the white wire end again to make sure nothing was grounding out. Then I took off with the intention of engaging the clutch and letting it turn over as I peddle to blow out anything in the chamber. As soon is I released the clutch lever IT STARTED and ran for a few seconds. Opened up the fuel valve and took off on a few powered runs up and down the street in total darkness, a light snow falling, and no lights (I know - not smart - but you know you would do it too).

    So I am thinking it was either:
    a) one of the wires was grounding out somewhere that I didn't catch
    b) too much oil in the gas at 18:1 instead of tonights 24:1
    c) choke was on last night and off tonight
    d) simply flooded last night and I got lucky today

    Either way, I am one happy guy.

    Now I need to polish up the build a little bit (shorten some cables, add a front brake, tiddy up the wiring, beef up the fender mounts, etc). I've got a few general questions but I'll post those in a new thread.

    Thanks you all for your help - this forum is an awesome resource! Cell phone pics of her after her maiden voyage:

    [​IMG]
    [​IMG]
    [​IMG]
     
    #11 Dymaxion, Jan 4, 2010
    Last edited: Jan 4, 2010
  12. Dan

    Dan Staff
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    Wohoo! Good news. Great build. Really like the Schwinn Cruisers. Gotta watch them fenders but lookin' good
     
  13. marts1

    marts1 New Member

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    Yes, you are correct, I woulda too :)
     
  14. freewheeling frank

    freewheeling frank New Member

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    funny how fickle these things can be, nice bike i also like the cruisers but am gonna stick with mbs for a while just bought myself 3 slant head grubbes for christmas, one other thing air leaks! havent had a big prob with the grubees but the hua sheng was difficult, jetting was a prob when i first started on this but live at 7200 feet and go over 9 alot, would love to start a thread for high altitude operation, any takers?
     
  15. Nougat

    Nougat New Member

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    Where'd you mount your CDI? Any trouble with the plug wire going by the pedal chain there, or heat from the motor?
     
  16. Dymaxion

    Dymaxion New Member

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    I put the CDI under the motor sitting on the bottom bracket. For now I simply zip tied it in place tied to the seat and down tubes and one tie also connected to the bracket for the peddle chain guard. Time will tell if the engine heat causes problems for the ignition wire since I have maybe 10 minutes running time on it so far but it is good wire from a cycle shop so I am hopeful. I put it down there so I can minimize wires as much as possible. The engine wires double back through the front mount so they are out of sight, and I am going to replace the plastic throttle with a better one and put a kill switch under the front edge of the seat. That way I can run the kill wires down the seat tube and out to the cdi below the engine as well. Can you tell I don't like wires everywhere?

    I can put up better pics later if you like.
     
  17. biken stins

    biken stins New Member

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    WTG.
    Nice ride !
     
  18. Riding Rich

    Riding Rich New Member

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    I got a brand new GT-5 just before christmas.

    I didn't run it cause im runnin a new PK80.

    I took it apart instead.

    So since this is seeming to be a common problem i'll tell you this.

    WHEN I TOOK THE NUT OFF THE MAGNETO MAGNET I NOTICED SOMETHING !!!!!

    The key used between the shaft and the magnet was too small.
    The magnet was floppin around like u wouldn't believe.

    So why's that bad.

    That key times the spark and if the spark occours at the wrong time the motor will never run.

    hhhhhhuuuuuuummmmmmmm.

    Take off the little square box where the wires come outta the engine.
    Loosen the nut off of the magnet.
    Hold the sprocket with a pc of chain to keep the shaft from turning.

    Once you have the nut off check 2 things.

    Rotate the magnet so the slot for the key is at 12:00.
    The slot should lean toward the sprocket.
    If not the magnet needs flipped.

    If the magnet wiggles when you turn it you need to replace the key.

    Also make sure you unscrew the connector on the top of the spark plug.
    The stock wire fits on the threaded part.

    Other than that i don't know.

    Check the ohms of the blue wire.

    Put the hair dryer away.

    My bike sits outside in 10 degree weather during a blizzard and starts right up easy.

    Check that magnet i'm really curious like i said i never ran the motor.
    I'm rebuilding it right now.

    Porting ECT.

    Good Luck
     
  19. manyguns

    manyguns New Member

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    I think you had flooded it.
    Tom
     
  20. exavid

    exavid New Member

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    Your description sounds a lot like a heavily flooded two stroke. The easiest way to clear a flooded engine is to remove the spark plug, shut off the gas and spin the engine over a bunch of times to dry it out. Then just replace the spark plug, turn on the gas and try starting it without the choke. If it fires and won't keep going then add some choke. Two strokes are easy to flood and with a crankcase fulll of fuel take more effort to clear than a four stroke where the extra gas is only in the cylinders.
     

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