bought a replacement engine and it wont start.

Discussion in 'Motorized Bicycle General Discussion' started by mathersi, Apr 6, 2011.

  1. rohmell

    rohmell Active Member

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    New spark plug, carby, CDI, what's left?
    Try switching over the magneto from your old engine
     
  2. mathersi

    mathersi New Member

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    ok i varified i have a spark when i tested it against the cylinder.

    i guess i have compression because of the glubbing sound when it doesnt start.

    for fuel..... im pushing the little button in and if i hold it fuel slowly leaks out of that area is that a check for fuel?

    and for im going to buy some black silicon sealer for my intake because maybe an airleak is creating my problem.




    also - can some1 give me steps on how to clear my engine,carb incase they are flooded?
     
  3. mapbike

    mapbike Active Member

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    if the engine is flooded it will cause the plug to be very wet with fuel after you whirl it over while trying to start it, if plug is basiclly dry it isnt flooded.

    Like I mentioned before, if you have fuel, spark, air intake and compression that engine will run unless it's out of time or as you mentioned possibly flooded.

    not sure what else to tell ya on this.
     
  4. mathersi

    mathersi New Member

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    i keep reading about sparkplug spacing? is that just the two rings that came around the sparkplug threads or do i need to do something else...?



    hopefully i can get it running tomorrow and use it
     
  5. mapbike

    mapbike Active Member

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    What you mean is "spark plug GAP" This is the space between the electrodes that the spark/fire arcs between, I set mine plug gap at around .028 - .030, if the gap is too wide or too close it will cause the spark to be weak.

    if you dont have one already just go to your local auto parts store and tell them you need a spark plug gapping tool and they can fix you up, that is a very inexpensive tool.



     
  6. mathersi

    mathersi New Member

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    maybe thats the problem? when i tested it against my cylinder the spark was very dull just a tiny thin line down to the bottom peice... i looked on some youtube videos and sparks looked much more electric then a single line that doesnt move around
     
  7. mathersi

    mathersi New Member

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    ok guys.... i have some great news !!!!!!! MY BIKE STARTED!!!! and i used it for a good 10 minutes.

    now for some more noobie questions :(

    1) i think i read somewhere that you shouldn't go passed half throttle for a while? is that because the bike cant go faster? it didn't feel like i could get to the same speed as i did on my other bike.

    2) im having the same problem as i did on my old bike, or maybe im not idling properly.... i do this: riding the bike at 20km/h then squeeze the clutch expecting the motor to keep running but not have a hold of tire ( idle position ). instead the bike just revs really loud and i end up hitting the kill switch.
     
  8. momentummotorgroup

    momentummotorgroup New Member

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    if you didn't drain the engine for winter storage it is more than probable that the gas in the engine ate through the cheap crap gasket paper, and that your situation could be one of lack of compression. The gunked up spot where the hole is was plugged then gave way, leading to first a loss of power then no turnover at all. Replace the gasket on the bottom of the jug and see what happens.. Also,change out the cheap stock bolts. Sick Bike Parts has a good replacement kit for this.. I have made it a habit on all my builds to a)swap out all hardware (nuts/bolts) with stronger higher grade stuff and b)take stock gaskets off and clean parts then replace those gaskets with higher grade ones. and c) clean out that gas tank before firing the kit up as a lot of times there's junk/rust in there that can clog your flow..
     
  9. mathersi

    mathersi New Member

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    its a BRAND NEW kit.

    im not able to go as fast as my old kit i had before ( im not sure if they go slow for the first while because i bought my bike used ).


    as for the idle thing, while im peddling if i disengage the clutch it jsut makes a really loud revving noise and i get scared so i kill switch it. basically i cant apply breaks and stop at a stop sign with the motor on, i have to kill switch it and start the motor up because that revving noise is WAY to loud and i feel like something might break.
     
  10. rohmell

    rohmell Active Member

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    Congratulations on getting your engine running.

    If your engine is revving up when not under load, then you have an air leak somewhere. Could be between the carb and the manifold, the manifold and the engine, or maybe the crankshaft seals.

    To check the crankshaft seals,you have to remove the magnet and maybe magneto on one side, and on the other side, you have to remove the small gear. Look for any seepage of oil where the seal is in the engine block, and around those areas.

    Did you adjust the idle speed screw?

    There are varying opinions as to how to run the engine when it is new. Some say to take it easy, some say to kick its butt, some say to vary the speeds.
    Make sure to run more oil in your mix when the engine is new for break-in purposes.
     
  11. rohmell

    rohmell Active Member

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    OK I re-read the thread from the beginning, and you wrote that the old engine ran perfect, so probably the carb is set up good, idle speed and so forth, so now you need to look for an air leak, because air is coming into the engine, not thru the carb's air intake, but somewhere else, so it revs up like that.
     
  12. mathersi

    mathersi New Member

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    thanks my face is actually very lit up right now :) i think shes gona be running perfeclty after i visit the store :D
     
  13. mathersi

    mathersi New Member

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    thanks a lot guys everything works great now,

    i really appreciate it
     
  14. rohmell

    rohmell Active Member

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    Glad to know everything's working good for you now.
    Enjoy!
     
  15. mapbike

    mapbike Active Member

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    Glad to hear you got-er going good mathersi

    the engine will run better when it gets broken in and everything is seated in properly, internals are a little outa wack before things wear in a bit, then in my experience the engine starts to smooth up and run much better, some do it quicker than others just depends on the engine.

    I had one smooth up good after about 150miles and another just started really running good at about 300miles, just do as someone suggested and run a little extra oil in the mix and I dont recommend going on long full throttle runs right off the bat, I did that and burned up an engine, it wasnt too lean and was running great and then I went on a 6 mile trip and run it WOT most of the way, that was a mistake I should have took it easier for a while and I think it would have been OK, so just to be on the safe side i would not run WOT for any long distance until a 100 miles or so on it, just my opinion which may or may not be 100% correct, but I dont see how it will hurt a thing to be a little easy on it for the first few miles so you dont over stress things before they get seated in good since the machine work on these engines is a little on the rough side.

    Peace & happy safe riding!
     

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