no top end rpm...

Discussion in '2 smokers' started by Chief Ten Bears, May 14, 2012.

  1. Chief Ten Bears

    Chief Ten Bears Been here awhile

    Joined:
    Oct 27, 2011
    Oddometer:
    427
    Location:
    Winnipeg
    I have a 1979 KE100, runs like a champ... but lately I've noticed something strange happening. when the engine gets hot/warm after riding for some time, when you give it throttle to lets say accelerate through the gears, it sputters, burbles, when you get up in the RPM... not like it wants to die, but just like you hit a rev limiter or something. It still idles fine, when its hot power seems a little down though... Any thoughts? Running to rich perhaps? This only happens once the engine gets hot after riding for a while, and only when its hotter outside at well...
    #1
  2. Harpua

    Harpua formerly josdavlar

    Joined:
    Apr 22, 2011
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    166
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    Edgewood, New Mexico
    One of my bikes did that a while back. Cleaned the carb and problem solved. Must've been some goop somewhere.

    If you haven't tried Pinesol, do it! It's awesome. I've found full strength works best.
    #2
  3. UnsureFooting

    UnsureFooting Title of User Here

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    Valve float?
    #3
  4. Tosh Togo

    Tosh Togo Long timer

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    :rofl

    [​IMG]
    #4
  5. stainlesscycle

    stainlesscycle Long timer

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    is this throttle position independent? if throttle position has no bearing it's either the rotary valve or ignition timing. if you can back off the throttle and it will zip to top rpm, it's generally jetting. depending on where your throttle is at, it's either needle positon, or main jet most likely. could be float height/float issue also. if float is letting fuel by, it could be rich up top and not rev out.
    #5
  6. JonnyCash

    JonnyCash turd polisher

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    My first thought was too rich on the main jet, as I've had that before, when trying to get my RD jetted in. But if it was running well before on that jetting, I wouldn't jump and start changing things around, it must be something else. Is your air filter clean? A dirty air filter would cause a rich condition. Overly advanced timing could create a "rev wall".
    #6
  7. pdxjim

    pdxjim Two Stroke Terror

    Joined:
    Sep 14, 2009
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    I had a KE175 that did that.

    The stock exhaust has extensive baffles and tubes that get clogged with carbon.

    I got a long drill and reamed out the exhaust and it fixed the problem.

    This was when I was about 18, so I might suggest cutting it open cleaning it out and welding it back up if I were to do it again.

    Might try cleaning the airfilter as well. Whatever the cause, it sounds like it's too rich when it comes on the mainjet.
    #7
  8. darmst6829

    darmst6829 Been here awhile

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    Redmond WA
    Check the flow from the fuel petcock.
    #8
  9. UnsureFooting

    UnsureFooting Title of User Here

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    So... that's a no... :D
    #9
  10. Chief Ten Bears

    Chief Ten Bears Been here awhile

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    Winnipeg
    Thanks for all the info and insight!
    #10
  11. wfopete

    wfopete Suffer Fools; Gladly!

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    Hey Chief,

    Before you go chasing all over trying to find the problem, check the basics first (fuel, air, plug). I doubt you need to replace a main jet but a dirty/clogged carb or exhaust might be your most likely issue. Timing? I doubt it, unless YOU changed it. Hell, it's only 30 years old...what could go wrong?
    #11
  12. Chief Ten Bears

    Chief Ten Bears Been here awhile

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    427
    Location:
    Winnipeg
    Thanks, I tend to agree... It ran fine all last year, not a problem... It ran fine for the first month I was driving it this year as well. I haven't changed any timing or jetting or anything.

    Its 30 years old, but only has 4000km on it, not that, that means anything...
    #12
  13. Hunsta

    Hunsta Have guns will hunt

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    Dismiss this if Im completely off base, as Im not familiar with the KE100 that well. Do they run reed valves?
    I had a 1977 YZ125 that had similar problems. Turned out to be the reed valves. Seems they were alittle worn out and the bike would sputter and run rough if you tried to give it too much gas up high. You would have gas it very slowly to get around it.
    #13
  14. SprintSix

    SprintSix Been here awhile

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    Dec 24, 2009
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    Ohio
    Failing oil pump. Mine did, it would break up in the mid range. Sounded lean but was really no oil and seizing. Add some premix to tank, mine revved out after I did. Still had to re-do the top end...again.
    Points timing. They do wear so after 30 yrs might be time to adjust.
    Failing coil or magneto.
    Worn carb needle could cause a rich condition in the mid.

    All from KE100 experience.
    #14