motorized bike won't start

Discussion in 'General Questions' started by conor mitnick, Apr 26, 2016.

  1. conor mitnick

    conor mitnick New Member

    I have my motorized bike and jut struggle to get it to start. I checked everything have compression spark and fuel going. So that's not an issue I try choke and it pops. Just doesn't start. It runs sometimes but then gets hard just changed the cylinder plug and piston and rings all new parts. Also goes very slow when it gets hot too. Sometime that happhens as well. Very weird. Can't figure out why. I checked carb its clean and float is where it should be. Appreciate the feedback guys thanks
     

  2. crassius

    crassius Well-Known Member

    not all cylinders fit all motors - also, sometimes when ordering pistons they send oversized because they think it will go in a used cylinder (numbers stamped onto top of piston indicate what oversize they are)
     
  3. conor mitnick

    conor mitnick New Member

    Thanks It Did Fit Fine When I Changed It Runs But Very Stubborn. I Just Can't figure Out Why.
     
  4. David Bogle

    David Bogle Member

    So how do you order the correct piston? Most dealers don't know what the numbers are for, where do you order from?
     
  5. crassius

    crassius Well-Known Member

    oversizes are not that much - each number is only about 20micrometers over, so you can get all the way up to a #4 piston before you get up to 3 thousandths of an inch over - I rarely do a top end for a customer since with labor it is better to just shove in a new motor

    when I do order pistons, I read the number, and hone off a thou or two from the cylinder to help match up the piston
     
  6. butre

    butre Well-Known Member

    if I'm doing a top end I replace the jug too. it's just easier that way.
     
  7. Is this a 2-stroke? What are you running for oil and mixture ratio? It may need a richer oil to fuel for lubrication.
     
  8. conor mitnick

    conor mitnick New Member

    I do use 50:1 ratio usually I always mix a thicker oil mixture. I would rather replace a plug then another motor. Now my friends bike seems to lock up when clutch is released like its acting as a brake now I don't know why. Also question off topic but what would a fair price to sell these bikes at and what is the best way to advertise them thanks.
     
  9. It seems like with the 2-stroke bikes they are selling for around 500-600 dollars here in Montana. The best way is typically Craigslist in order to get the word out that you have something for sale.
     
  10. 50:1 is actually pretty light and with new piston and rings you may want to go 25:1 for the first tank in order to give proper lubrication to the rings.
     
  11. conor mitnick

    conor mitnick New Member

    Thanks appreciate it
     
  12. Aytime!
     
  13. David Bogle

    David Bogle Member

    Thank you, it's nice to know what the meaning of the number is, I've been told more than once that the number was absolutely meaningless.
     
  14. Ytyukon

    Ytyukon Member

    just a thought.i was running a bit rough. I ditched the fuel filter. direct into carb...running much better without it.
    i think the filter is kinda a useless thing.
     
    Timbone likes this.
  15. sully1617

    sully1617 Guest

    just a thought. try reversing the wires on the mageto if you disconnected it in your rebuilding it may have been connected backwards accidently. just a thought
     
  16. crassius

    crassius Well-Known Member

    the rubber control disk in petcock sometimes deteriorates and sends small rubber pieces down the line - 2nd filter catches those

    they're cheap, when clogged, replace
     
  17. Ytyukon

    Ytyukon Member

    make a mesh screen for the carb intake, easy ways to avoid using filters that arent necessary.
     
  18. rjs1617

    rjs1617 Guest

    it's entirely possible that the piston fits the cylinder when installed but as it heats up the piston swells from heat and locks in the cylinder. double check what is going on in there. if you have a scored cylinder now or scored piston then it is too large by as little as 1 one thousand of an inch and may need to be changed out again for a slightly smaller diameter piston. also you may need more oil for break in or for that matter less oil. look for the obvious things sometimes they are easy to overlook because we get so focused on something else
     
  19. rjs1617

    rjs1617 Guest

    i forgot to mention, also check the gap on your spark plug. this can cause delayed spark which will make it hard to start and run
     
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