I hate it when they do this.

Discussion in 'Motorized Bicycle Trouble Shooting' started by crassius, Dec 14, 2016.

  1. crassius

    crassius Well-Known Member

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    Putting miles on my new test bikes lately (when repair jobs & weather permit) and one quit on me today. Was pulling up a hill fairly aggressively when it started missing a bit & loosing power, then quit about 100 feet farther up the hill. Looked it over well, saw nothing, checked wiring, unplugged kill wires. Pushed it to top of hill and came down, and it started again. Ran a bit crappy with intermittent missing back to shop.

    Drained carb into glass jar to look for water as I had added fuel before starting out, but didn't see anything - checked all and reconnected wires.

    Rode around for a couple miles with no problems.

    Now, if I never figure out what happened, will I trust it on a long ride?

    Troubleshooting after the fact just kills me.
     
  2. ZipTie

    ZipTie Member

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    Steep hill and sputtering out...float issue maybe from the angle?
    Zip
     
  3. curtisfox

    curtisfox Active Member

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    Sounds like bad gas to me, run fine after you put new in.Or like Zip said, float angle...............Curt
     
  4. crassius

    crassius Well-Known Member

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    yeah, might have been a water drop that went thru so wasn't seen when I drained carb - this is one of two identical bikes, so float angle shouldn't be it unless the carb has a flaw - also might have been a funny spot on wire connector that rubbed clean when I replugged them

    I can only pedal 1/2 a block and only walk a bit less than 3 blocks, so I'm a bit nervous about trying a long ride : (

    Just hoping running it a while around the near area will show what's wrong or show that it is OK now.

    EDIT: I should also note that this bike has been up that hill three times before during testing with no problems.
     
    #4 crassius, Dec 15, 2016
    Last edited: Dec 15, 2016
  5. sbest

    sbest Member

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    I had an XT600 that I bought brand new in 1985.
    Rode it 1 year, which was the warrantee period when it started shutting down for no reason. Would shut down for a couple seconds, then start back up. It got worse with time.

    It got so bad that as I gunned it out into traffic it would quit and toss me over the handle bars, and THEN it fire back up flinging me back on the seat! Not safe at all.

    The dealer was good about it. It rarely ever happened at the dealership. They only charged me for the parts tried and minimal labour for what would be servicing anyway.

    Finally they found it. Protective varnish coating inside the steel gas tank was breaking down causing almost invisible scales that would block off the petcock filter. Shut the gas off or shake the tank and the fuel would flow again. They pulled the petcock filter and installed an inline filter.

    [​IMG]
    (stock photo identical bike)
    100mph dirtbike
     
  6. ZipTie

    ZipTie Member

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    If you think about how small the hole is in a carb jet any micro gunk can clog em if even temporary. I would imagine Crassius that you remove and toss the upper petcock gas filter? I have been tossing mine, for good or bad? What do you guys recommend on the little petcock filter????
    -sbest, I had a meager 1972 YZ125 Yamaha dirt bike when I was a kid that had so much torque and compression it would rip the spokes clean off the rim and blast so hard with a blip of the throttle and when it kicked in after a one moment delay I needed a death grip on the bars. Those old 2 strokes were scary fast and fun. I could only imagine a 600cc 2 stroke. I would sure like to have one again.
     

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  7. crassius

    crassius Well-Known Member

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    I like both filters - tank filter protects rubber in the petcock, and line filter protects carb when rubber from petcock begins to shred with age.
     
  8. ZipTie

    ZipTie Member

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    That is too funny Crassius... but full circle protection. Ever had or seen a tank filter clogged?
     
  9. crassius

    crassius Well-Known Member

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    yes, just blew thru it and replaced
     
  10. crassius

    crassius Well-Known Member

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    well, bad weather lately had me doing only short rides on it, with no problems

    today, it quit at same place on same hill - hit tickler and couldn't tell about gas flow, so opened gas cap - started right up

    rode some on level road and started to spit & sputter, opened gas cap and no change, still rolling so hit tickler, no start

    got off and looked without touching anything, started up fine after a min

    got to shop, checked fuel flow, checked wire connections - rode a bit & it quit again on level road at moderate speed

    when it runs, it runs smooth and fast - always sputters a bit before quitting - always starts right up after about a minute - never quits on the run-bench

    beginning to hate this POS
     
  11. Kioshk

    Kioshk Active Member

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    t'was just a gremlin:

    [​IMG]
     
  12. curtisfox

    curtisfox Active Member

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    Almost sounds like a vapper lock................Curt
     
  13. crassius

    crassius Well-Known Member

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    got some bad weather coming again, and a few other things to finish

    will have to start replacing these new parts with other new parts to see if I can find the problem

    seems to be somehow heat related as tho something expands or moves when hot - so far am thinking may be electrical
     
  14. ultralight01

    ultralight01 New Member

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    Sounds like something got in the carburetor. Or you've got junk in the line or tank. Maybe a carb replacement will fix it, if not the magneto is getting worn out.
     
  15. crassius

    crassius Well-Known Member

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    pretty much convinced it is heat related, and most likely ignition - while coasting with motor dead, I hit tickler and see fuel moving, but letting out clutch gives not even a pop

    realized last eve that I never tried choke when sputtering started, so should try that when weather eases up
     
  16. crassius

    crassius Well-Known Member

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    what's really frustrating is that by the time I get off the bike, no matter what I test or how I test it - everything is good and motor starts right up
     
  17. crassius

    crassius Well-Known Member

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    got a break in rain today & was about to change CDI - looked just a bit funny, so I tried to see inside rubber plug and that was hard to see, but also didn't seem right - unscrewed plug wire from CDI and under good light I could see that the spring that should have gone over terminal nut was sideways up in there so that only the rubber boot was holding it in contact with plug - too cold & wet to ride today, but I'm thinking it's fixed

    checked 4 other CDIs in this set of kits and all were crooked to some degree, but not completely sideways - all straighten out easily, but I'll need to remember to check them before selling
     
  18. Chaz

    Chaz Active Member

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    Great catch, crassius. You found the gremlin.
     
  19. crassius

    crassius Well-Known Member

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    POS chinese bikes - froze riding it as I couldn't wait to see if it ran OK - it don't

    back to replacing parts : (
     
  20. crassius

    crassius Well-Known Member

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    replaced CDI - no good
     

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