wont start and when starts bogs down and dies
  • vispro
    Posts: 13
    i have a 2001 yz 125 all stock and i just put a new plug in last week and 2 days later i went to the track and it was riding fine for 2 hours then i took a break and started it up to go ride again but it started fine and as soon as i took off it bogged down and died and now will not start back up and i have plenty of spark and i took plug out and cleaned it and it started again but then it bogged down and died 10 seconds later?
  • TheDirtRiderTheDirtRider
    Posts: 1,844
    Classic case of a bad top end. How is the compression?
    ----------------------
    -Jimmy
    image
    Thanks to my sponsors: Oneal, Vortex Racing, Pirelli Tires, Amsoil, Smith Optics, Twin Air
  • vispro
    Posts: 13
    i didnt check that and what stuff would i have to buy to rebuild the topend
  • vispro
    Posts: 13
    i didnt check that and what stuff would i have to buy to rebuild the topend
  • NZriderNZrider
    Posts: 5,156
    it could be just flooded real bad. my yz did exactly that this week. float valve stuck open while it was parked was flooded real bad so push started it took like 3 pushes to fire up then held it wide open until all the fuel and oil cleared out then was good as gold again.
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • vispro
    Posts: 13
    ya ive had people tell me clean carb, blew engine and bad topend but i dont know yet oh an i had person tell me to check my reeds
  • NZriderNZrider
    Posts: 5,156
    well those are some good suggestions. have you looked into those things yet?
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • vispro
    Posts: 13
    i left it at my dads and he is going to tear into it this weekend so ill get back to u guys to tell u if it worked or not
  • jordan2010jordan2010
    Posts: 47
    I've had exactly the same problem in the past and found it to be due to flooding of the carb so badly that it took me over 10 minutes to get started again. Good luck, hopefully it won't cost you too much!
  • vispro
    Posts: 13
    ya i cleaned the carb and it was clen as could be and the reeds r clean and not cracked so im guessing a top end now?
  • jordan2010jordan2010
    Posts: 47
    If you have the abilities to tear it down then good luck. You were using the correct spark plug?
  • vispro
    Posts: 13
    it has plenty of compression so now im guessing something electrical? maybe something with the ignition and the compression was like 145 so its good on the top end
  • vispro
    Posts: 13
    it has plenty of compression so now im guessing something electrical? maybe something with the ignition and the compression was like 145 so its good on the top end
  • yamadogyzyamadogyz
    Posts: 4,386
    your bike dosent have a hot start dose it? you may have to let it cool down a good while then kick it and hopefully it will start
    -Ron Boyas 915 remembered-
  • ForceForce
    Posts: 1,608
    a 2 stroke doesnt have a hot start.

    visp try a new plug first, sometimes it seems that it sparks well but it's not enough. if a new plug doesnt work it may be another electrical problem.
    ////////////////////////////////////////////////////////////

    If you ride like there's no tomorrow, there won't be.

    If you want to come in second... follow me!


    2006 YZ250

    image
  • vispro
    Posts: 13
    i fouled a plug then got a new one and it did same thing so i put old plug back in and it still did same thing
  • yamadogyzyamadogyz
    Posts: 4,386
    now it makes me think about the jetting
    -Ron Boyas 915 remembered-
  • badcoil
    Posts: 53
    I would not play with the jetting if it was working well before.
    Could be a small leak in the head or base gasket... water makes it way to the combustion chamber. Check for white smoke out coming out of the exhaust.
  • vispro
    Posts: 13
    i got another new plug and idk if it was a bad plug but it ran for 20 minn then died and now the plug is making no spark at all so i got a new plug again and it started fine but i havent rode it that much yet and if this plug goes bad again wat could it be any suggestions oh and i got compression up to 160
  • jayriderjayrider
    Posts: 1,322
    strange, 160 pretty good though.
    -----99 RM 125 04 YZ 85-----
  • TheDirtRiderTheDirtRider
    Posts: 1,844
    160 is pretty good. What do the spark plugs look like when they're fouled? I mean I know they're black but do they have heavy oil deposits on them? Does your bike smoke a lot when its running?
    ----------------------
    -Jimmy
    image
    Thanks to my sponsors: Oneal, Vortex Racing, Pirelli Tires, Amsoil, Smith Optics, Twin Air
  • yamadogyzyamadogyz
    Posts: 4,386
    no to me it seems as if you have low compression, you will be riding and you bike will feel slow and bulky, then it just wont start
    -Ron Boyas 915 remembered-
  • jayriderjayrider
    Posts: 1,322
    ray 160 is fine anything under 120 is bad
    -----99 RM 125 04 YZ 85-----
  • yamadogyzyamadogyz
    Posts: 4,386
    no, i was decribing about how you can tell if you fouled a spark plug
    -Ron Boyas 915 remembered-
  • vispro
    Posts: 13
    i rode it for like 15 min and it seems to run fine for now i started it up a few times and its fine but i guess time will tell
  • vispro
    Posts: 13
    ok havent been on here in a while but i got new plug it worked but then i rode 6-8 hours and it ran fine and then it sat for 2 weeks i started up it started fine but it died again after 200ft and i got new plug and now it wont even start and shop told me everything passed in electrical department so i have no clue now but could i maybe ran the next hotter plug?
  • flyinghighyz250flyinghighyz250
    Posts: 16
    i whould check ur air and idle screws u shouldnt be fouling that many plugs
  • NZriderNZrider
    Posts: 5,156
    everything may have passed in the electrical department when they tested it but i'd almost guarantee its an electrical fault.

    it starts fine then as it vibrates/warms up something is moving or deforming and causing spark voltage to drop, the plugs probably arent really fouled, just fouled enough to stop a weak spark from making the jump.

    i would suspect the stator first since they seem to be the most common failure in ignition systems
    *********************
    Winning is 90% rider and only 5% bike, the rest is luck
  • Jasquatch
    Posts: 1
    Same thing happened on my buddys 125 its the float
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