Stupid dirt bikes

Discussion in 'Mini Racing' started by V5 Racer, Mar 12, 2012.

  1. V5 Racer

    V5 Racer Yo!

    Ok, help me out people. Both bikes always get fuel that has stabil in it, have not been parked for more than a month or so.

    JR50. Starts, runs for a few seconds and then dies. Choke on, choke off, no matter. Cranks, runs, dies. Have pulled carb and jets to clean, it wasn't too bad but made zero difference.

    CRF70. Won't crank. Was the easiest cranking bike we ever had back in December, now it won't crank. At all. Pulled carb, it was funky in a green kinda way. Cleaned, still no joy. Every now and then I get a pop. I think the pilot is still clogged, I didn't get the warm fuzzies when I worked it over. It should still crank on the choke, though, shouldn't it?
  2. raddad13

    raddad13 Well-Known Member

    If you havent already, I would try new gas or from a different jug just to rule that out.
    For the slow jet I use an E string from a guitar. It seems to be a good fit.
  3. Mook

    Mook Well-Known Member

    fresh fuel? drain the old gas out completely ditto on the gas in the float bowl.

    verify that the pilot jet is clear. can you see through it?
    use a high "E" guitar string on the pilot jet.
    generally speaking an engine will not start if the pilot jet is blocked.
    clean the tip of the float needle with alcohol and the float seat with a Q tip and alcohol.
    ideally the carb(s) should be soaked in an ultrasonic or at least a gotten quiet warm in a pan of water on the stove. then use compressed air through all the passages.
    (that is before you re-assemble it all...)

    go get new spark plugs as well.
  4. Mook

    Mook Well-Known Member

    hey Jason!:beer:
  5. backcountryme

    backcountryme Word to your mother.

    Check spark too. I had a cdi that would trigger the coil, but was breaking down. Very weak looking spark. Changed CDI and it started on first kick.
  6. ACDNate

    ACDNate Well-Known Member

    Eh jets are cheap, I don't believe in cleaning them anymore. Definitely look to the pilot jets in both.
  7. V5 Racer

    V5 Racer Yo!

    They both have fresh gas.

    Will get a new jet for the CRF.

    Will reclean the JR.

    Will then report back. Thanks.
  8. TurboBlew

    TurboBlew Registers Abusers

    crf should be easy peasy to diag. REmove the intake boot and try some starting fluid.
    2 8mm bolts and you can have the carb off for a quick cleaning.

    If you store them with ethanol free gas/stabilizer it will extend storage to at least 3 months.
  9. iomfan

    iomfan Well-Known Member

    I've been using the blue (Marine formula) Stabil the last year. I use it in the street bike, lawn mower, TTR125 - anything that sits very long. Everything I use it in always cranks, idles and runs normal. I find it at Walmart and Advance Auto.
  10. V5 Racer

    V5 Racer Yo!

    These both had the red stabil in the gas. Too bad it made me cranky instead of the bikes. :D
  11. Kurlon

    Kurlon Well-Known Member

    Check the valves on the 70, if they're at all tight, it'll be a PITA to fire up.
  12. Cam Morehead

    Cam Morehead Husband, Dad, Racer

    I only use Ethanol free gas.... My 100 and 50 have been in the trailer since Nov..... I got them out this weekend and did wheelies for hours..... No carb cleaning. Good luck bro. I also turn the gas off and run them until they cut off.
  13. Mook

    Mook Well-Known Member

    a word of caution regarding "starting fluid"-
  14. Mook

    Mook Well-Known Member

    whatsa PITA ?
  15. Mook

    Mook Well-Known Member

    .. oh i get it - pain in the ankle.
  16. V5 Racer

    V5 Racer Yo!

    There's a story out there somewhere about my misadventures with starting fluid and a Harley Davidson. Basically it backfired out of that sideways-on carb, sprayed gas all over my jeans and lit my ass on fire. Woo hoo. "Tale of the dragon", indeed.
  17. ToddClark

    ToddClark f'n know it all

    im betting fuel.
  18. Venom51

    Venom51 John Deere Equipment Expert - Not really

    Maybe he should have his injectors cleaned. :D
  19. V5 Racer

    V5 Racer Yo!

    Where are you getting ethanol free fuel? Only fuel like that I can get locally is VP pump, it's 8 or 9 bucks a gallon and 110 octane.

    I'm betting running them dry is doing the trick, I do that with my gensets and never have a problem. Guess I'll start that doing with the dirtbikes.

    Can I help you two with something? Hmmm?

    Last edited: Mar 13, 2012
  20. TurboBlew

    TurboBlew Registers Abusers

    the test is really simple. Get an old cigar tube and put a permanent black/tape line in the middle or a lil lower on the outside of the tube. Fill the tube to the line with fuel. Then add some water and shake vigorously. If the level you filled to is higher... the fuel is not ethanol free.

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