Rear wheel locks when disengaging clutch, no engine start is this normal?

Discussion in 'Motorized Bicycle General Discussion' started by Aqua, Jun 11, 2010.

  1. Aqua

    Aqua New Member

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    Hi guys, I am a bit of an engine noob but as a fun project I put a 49cc chinese ebay special engine kit on my 1993 Pro-flex :D

    Anyways tried to start it today by rolling own the driveway and popping the clutch but the chain just locks up and the engine doesn't start (the rear wheel just skids).

    Do I need to use more force or go faster? Just checking because I don't want to wreck anything.

    .duh.
     
  2. TheBeak

    TheBeak New Member

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    To start it make sure your gas is on and hold the clutch lever and start peddling, then release the lever while giving her a little throttle and keep peddling. should start right up

    Welcome to the Forum, everyone here is a great help. Hope you're good to go
     
  3. Mind_Reader7

    Mind_Reader7 New Member

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    A little more force I guess. Ride it down the street, until you're at your average speed and try.
     
  4. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    If the bike rolls O.K. until you release the clutch, then you need a little more speed and/or weight. Remove the plug and spin it over a couple of times to make sure you aren't hydro-locked.
     
  5. maximillian

    maximillian New Member

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    Is it a slant head? i found that my slant head needs more force to start
     
  6. taddthewadd

    taddthewadd New Member

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    If it isn't hydro locked then try going faster and try bouncing your weight down on the pedals right as you pop the clutch. This will give you more traction on your rear tire. Are you really light? I weigh 165 and don't have to bounce down but if you are like 120 or something maybe that is why you are having a little problem. My first check would be what bike guy joe said to remove the spark plug and try. Not only will this see if it is hydrolocked but will reveal if there is another problem with the drive train. If it goes real easy with nothing like the chain or sprocket locking up then put the spark plug back in and try the bouncing your weight thing.
     
  7. GearNut

    GearNut Active Member

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    I sometimes go so far as to stand up on the pedals while pedaling then hit the seat with my butt (basically falling onto the seat with all my weight) as I simultaneously and quickly release the clutch. Just like bump starting a motorcycle.
     
  8. Aqua

    Aqua New Member

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    Ok pardon for the dumb question but is the sprocket supposed to lock like that at low or no speed when the clutch is out?

    Reason I ask is when I first installed the clutch cable, the clutch was stuck and would not allow the sprocket to turn even when the clutch lever was pulled all the way over, so after searching these forums I went into the star nut side and loosened it a bit, and wiggled the big plate circle thing so it released when the lever was pulled (seemed like it was just stuck from sitting or something).

    I assumed from the instructions when the clutch is out, the sprocket is locked and when it is in, the sprocket can move right?
     
  9. TheBeak

    TheBeak New Member

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    Yeah Its a little late here and i just woke up so i could be out of it. But yeah that is right
     
  10. kyl 46&2

    kyl 46&2 New Member

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    is your clutch pushed all the way in? when i first started playin with these motors i didn't know that it took a good amount of force to get the clutch all the way in(disengaged) i went so far as to buy a second kit thinking my first one was a lemon.
     
  11. Aqua

    Aqua New Member

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    I assume so since when I pull in the lever and lock the hand lever I can move the wheel (sprocket).

    So to start the engine this is what I am doing.

    Open choke, gas.

    1) Pull in the hand lever and lock it with the pin which pulls the clutch and I can move

    2) Pedal up to speed

    3) Release the lock pin on the clutch hand lever

    4) Engine supposed to start?

    right now all it does is lock my tire and lay a nice patch of rubber... not too good for the chain either I would imagine.
     
  12. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Yes, that sounds right....now take the plug out as suggested and let us know what you find. Does it turn with no plug If not, you have other problems.
     
  13. Aqua

    Aqua New Member

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    OK, so I removed the spark plug completely, on the bike stand I cranked up the peedals and let out the clutch, locks.

    I put the plug back in and tried, same thing, locks., I am not getting that "whoomp whoomp" noise anymore either that I got the first time we tried it (had some issues with the chain tensioner when the wheel locked before so I had to fix that first)

    Theres no sound at all now just locks up :( Hope I didn't break it when we were first trying (the chain jammed at one point)

    EDIT: When you say "spin it up a little" do you mean do the clutch in/out process with the spark plug removed, or should it move even without the clutch lever in?
     
    #13 Aqua, Jun 12, 2010
    Last edited: Jun 12, 2010
  14. Aqua

    Aqua New Member

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    ok nm, it does infact "turn over" when I turn the wheel with the clutch out. I didnt realise it took that much force.
     
  15. Aqua

    Aqua New Member

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    bah, I got it to turn over once without using the clutch, now it is completely jammed again when engaged. Since it is just a little 49cc I should be able to turn it by hand. I guess I got a dud. I get it now though at least.


    Is there anything simple that could have gone wrong that could be fixable causing the jam? It wont turn over with spark plug out so I assume something is very wrong inside.
     
  16. CoastalCruiser

    CoastalCruiser New Member

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    SOUNDS LIKE MAYBE A HUNG RING. (sorry damn caps). Yank the head and carefully pull the cylinder and see if you have a broken or unseated piston ring hanging up on one of the ports. If so then you'll need th replace the top end or get a replacement from your dealer. If that aint it then you might have a dangling rod bolt.
     
  17. Aqua

    Aqua New Member

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    ok would this explain the ability to turn over one time then jammed the next? frigging POS I spent 3 days straight building this thing :p
     
  18. CoastalCruiser

    CoastalCruiser New Member

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    Yes. If the piston can't go up and down then the crankshaft won't go round and round.
     
  19. Aqua

    Aqua New Member

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    well I figured out the problem, took off the head, no issues at all.

    Turns out it is just the chain slightly jamming in the sprocket case, I feel kind of dumb... the bike has rear suspension so every time it is sat on the chain goes a bit lose and when the clutch is released it jams the chain.

    This is a tough one maybe I will post another thread on the chainline issues.
     
  20. GearNut

    GearNut Active Member

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    It sounds like you could benefit from a spring loaded chain tensioner.
     

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