KLR 650 develops high idle when warm

Discussion in 'Thumpers' started by Rob Healy, Jun 30, 2008.

  1. Rob Healy

    Rob Healy Metropolis Hopper

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    Hello All,

    Searched through the threads and ingested a lot of Stu's advice on wrenching on your KLR before posting this. I'm not looking for a diagnosis (well maybe a little diagnosis) on this problem as much as I'm looking for some courage to undertake the repair.

    I have owned this used KLR since January and put about 3,500 miles on it since then. Just passed the 10K mark last week and threw 520 miles on it this weekend doing my Jersey City to Boston 2-Tank Evaporator Trip.

    Anyhow, on the return I pulled into a rest stop and while parking realized my idle was up to like 1700 RPM. I've had the bike creep up to 1500 from my normal 1300 in strange weather, but this was excessive. I got a coffee, had a cig and restarted it and all was back to normal around 1250 to 1300.

    That was in no. CT. By the time I approached traffic near the GWB, I went to make a stop and when I pulled in the clutch the thing was at like 4000 RPM!

    I cracked the throttle to see if it was a stuck cable. No dice. Pulled over after the bridge and looked to see where the stop was in relation to the idle screw on throttle release. Was resting fine on the screw. Sat for a minute or two scratching my head and was on my way again. When starting, Idle was down to around 2000.

    Once I got back to JC the thing was howling again. Parked her for the night.

    Took her up to my garage the next day and when I started the bike, all was fine. Within a minute of her idling, i noticed the RPM creeping up to 2K. By the time I got the 0.75 miles to my garage idle was around 3K.

    So, throttle return is out of the question. Choke worked as expected when I started her the next morning. When I wanted no enrichment, I killed the choke and the RPMs went to normal.

    From what I have read, this seems like it must be time for intake valve adjustment? I'm just saying, I got the bike with 7K and it's now got 10.5K with no other servicng aside from 2 oil and filter changes.

    Safe to say it's time for the valves to be tended to? The guy I got the bike from never gave me the owner's manual so should I do a bunch of other servicing at this mileage mark?

    Thanks much,
    Rob
    #1
  2. CA Stu

    CA Stu Steer with your face! Super Moderator

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    I've seen a small rock get stuck in the linkage where the cables terminate on the side of the carb more than once.
    It's only one screw to remove the assembly from the carb body and take a peek...

    I'll bet if you do the valves, you will find the problem.

    Check the fitting on the left side of the carb where the enricher (choke) bolts on. It's common to crack the plastic there...

    With the tank off and the carb, airbox, choke, and carb boots right there just take a look at everything and you'll find it.

    Thanks
    CA Stu
    #2
  3. reverend

    reverend Adventurer

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    This sounds like a vacuum leak. Though just when it's hot...?

    It wouldn't take that much time to loosen the carb and twist it, then pop the cover and bowl off and just inspect and clean.

    Torn diaphragm (would that cause your issue? no idea)?

    Baffle between carb and cylinder torn?
    #3
  4. farmer fred

    farmer fred Banned

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    Vacuum leak, or stock lean jetting. Has the idle screw plug been drilled out?
    #4
  5. Rob Healy

    Rob Healy Metropolis Hopper

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    THanks for the suggestions all.

    Idle has not been drilled out. The carb is in nice, stock shape.

    I've been road cruising on the old shovel for the last 3 weeks, so I've been lax about tracking this down.

    Will post results upon fix
    #5
  6. Hondo

    Hondo What if it's a Samsquamch?

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    The next time you see it, physically confirm that the throttle linkage is at the idle stop at the carb.

    Make sure that the choke (enricher) cable is not have any signifigant tension at the carb connection point.

    I'd also recommend that you check the bands/clamps on the carb boots and make sure they are tight.
    #6
  7. grit.grease

    grit.grease moto hobo

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    i would guess vac leak too, a crack or a hose fitting that expands with heat.
    #7
  8. WR_guy

    WR_guy Been here awhile

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    A vacuum leak would make it pop or backfire a lot.
    #8
  9. zaner32

    zaner32 In over my head

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    If it's a vacuum leak, you should be able to find the leak using some ether. Just spray around the carb or vacuum lines. You should hear it rev up if there's a leak. Ether is not very good for the engine though, but I have found a lot of leaking vacuum lines this way.

    Make sure your throttle linkage opens freely and closes freely when the handlebars are at full lock (both sides) and in the center. Like mentionned earlier, a visual at the carb making sure the throttle returns at its idle stop is a good idea.
    #9
  10. tbirdsp

    tbirdsp REMF

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    Lots of good suggestions, but I would just go for a good carb clean first. I've seen a dirty carb cause a "hung" idle like this.
    I doubt it's valve related.
    #10
  11. Epicrat

    Epicrat n00b

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    :baldy Experiencing the same thing on my KLR650, did you every figure out what was causing it on your bike. Thanks
    #11
  12. Beezer

    Beezer Long timer

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    Leaking enricher is my first guess, then mebby the diaphragm(s).

    Has the slide been drilled? That makes the throttle more touchy & magnifies a small problem.
    #12
  13. feetfirst

    feetfirst n00b

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    OP sent me a reply as I was having the same issue. In the spirit of posterity here it is:

    [the problem was at the grip at the fastener from the cable. I never thought to look as that little boot is always over it and couldn't understand how it could come loose but all I did was pull out the small amount of slack, tightened the nut and no more fast idle!"
    #13
  14. His Pistolship

    His Pistolship Kp calm, shoot alfas

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    But how would that change when the bike heats up? My KLR has the same high idle when hot, when I have been in stuck in stop and go traffic for a long time. But when it is running cooler, I only have a little upwards creep with the idle speed. It hasn't gotten worse than 2000 rpm yet, so I have just ignored it. I just figure it is the result of an older carburated bike. (2001, 13,000 miles).

    I will check the cable however. But that doesn't explain why it gets worse when the bike heats up. I am interested in more suggestions.
    #14
  15. tasslehawf

    tasslehawf Been here awhile

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    Heh. I am having this problem as well. The choke is definitely giving me problems, as it is currently broken and I'm waiting on parts to fix it (hoping this is will fix the high idle, but we'll see).

    #15
  16. Beezer

    Beezer Long timer

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    well there is a pull cable that returns you to idle... if that is set correctly it should be able to overcome anything up to "boulder" size that gets stuck in the works.

    as for the enricher... make yourself one of these from a spare 12mm:

    [​IMG]

    then you won't break the bugger. I can even undo the enricher with the tank on
    #16
  17. Beezer

    Beezer Long timer

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    BTW, when you twist the throttle on a CV carb you are opening a butterfly valve that lets in more air, but that also changes the pressure on the main diaphragm. the diaphragm lifts the "real" throttle valve and the fuel metering needle.

    any air leak on the engine side of the throttle valve is sensed by the diaphragm as a more open throttle position

    a leaking main diaphragm (torn, hole, etc) results in less lift and the engine will not go over about 4000 rpm

    not sure what a leaking anti backfire valve would do because I haven't had to deal with that one
    #17