KLR650 jetting

Discussion in 'Thumpers' started by grinder96, Jan 30, 2008.

  1. grinder96

    grinder96 Long timer

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    Before you start flaming', I did a search for "klr650 jetting" that return me no useful answer!!!

    Now I have a 87' klr650 that I ride from Pasadena CA (900' ele) to the local mountains (5000' ele?). It accelerates good but pops on decel, sign of running lean. It has a K&N air filter and a Supertrapp exhaust. Smog stuff gone.

    My thought was to perform mods and test them one at a time in this order:
    1) The .22 mod. (washer under needle)
    2) The drilled slide mod (point of no return)
    3) Start messing with jetting.


    Will the .22 mod clear up the popping?
    Anybody regret the drilled slide mod?
    I have read the CV carbs self adjusts well, has anyone felt the need to change the jetting?

    TIA for your replies,
    Turin
    #1
  2. CA Stu

    CA Stu Thanks Super Moderator

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    Odds are you have an exhaust leak, not bad jetting.
    Check the nuts on the cylinder at the exhaust for tightness.

    Read this

    Thanks
    CA Stu
    #2
  3. Tazman

    Tazman Tazmanian devil

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    Okay a couple of things here.

    first, you are right, deceleration popping typically means you are running lean. there can be a leak but lean is a more common problem with the klr. You are also running a KandN filter. you can help yourself 3 ways here.

    1. 22 cent mod will introduce a little more fuel.
    2. you need to adjust pilot screw open more. it comes stock very lean.
    3. Use another filter. like a UNi Filter. once you do the above mods you will ned a touch more air. the uni filter will do that. or you can remove the snorkel, or drill holes in the top of the air box.

    then Ride it. for at least a couple of tanks, before you start drilling holes and stuff. If your trying to just improve the performance that will do it. if you are tying get all you can out of the bike then start drilling and buying new jets, you will also need another aftermarket needle. the KLR6650 faqs page does talk about an exhaust leak but references lean jetting as more of common problems. the symptoms can be the same.

    you can also check out KLRworld.com/forums if you do a search there you will get some hits and alot of help, as well as here.

    Good luck.
    #3
  4. kdxkawboy

    kdxkawboy Mr. NVKLRGirl

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    While it may just be my personal preference, toss the K&N and go with a NoToil or Twin Air filter. With the new filter go with the NoToil oiling system (need to start with an air filter that has never seen dino based filter oil). I've found where dust, water and mud will get past the bottom seal of a K&N in general have not had good luck with them in the dirt.

    Stock jetting works for your elevation. Once the bike is doing most of its traveling above 3000' you can use the factory recommend high altitude jeting. Once you are mostly above 6000' dropping the main jet one more size brings the engine back to norm.

    Drilling out the cap so you can adjust the pilot screw is the best change you can do at this point. If you want to play with needle I'd recommend going with the Dynajet kit. Big advantage is the Dynajet needle has grooves that llet you play with the needle height and their needle has a more standard profile that helps eliminate the just off idle lean malady of modern, EPA compliant bikes. You can also get other needles from your dealer that will do the same. With the Dynajet kit I've always found their Stage 1 jetting to work best for a KLR. And drilling out the air box does help a little bit.

    Drilling out the slide wont change jetting, it just speeds up the response of the slide to changes in air pressure above and below the diaphragm chamber.

    Pretty much everythihng you need to know about your KLR can be found in BigCee FAQ
    #4
  5. eaglemike

    eaglemike Been here awhile

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    Drilling the slide would close to last on the list. If you do - drill 7/64" - the 1/8" suggested by DJ has proven to be too big almost all the time.

    The stocck needle is lean until it's all the way up, then it's too rich. The DJ neelde is best for a stock engine. The KLX needle (part numbers in the bigcee FAQ) is nearly as good for a stock engine, and better for a mod'd engine.

    If you do change the needle start with a 145 or 142 main jet with the DJ needle, clip in the second groove from the top. #4 washers can be used to shim the needle, making finer adjustments than the gooves.

    With the KLX needle you'd need a 138 to 142 main.

    The Uni filter flows the best, proven on a flow bench - other things being equal. K&N flows less than stock, and harder to seal properly. I like the No Toil oil and cleaning system, works well.

    The above suggestions are from Cary at Schnitz Racing and my own experience. I've been using a wide band recording sniffer to verify things....

    all the best,

    Mike
    #5
  6. grinder96

    grinder96 Long timer

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    O.K. new game plan!

    1) Check the exhaust first, that is simple enough!
    2) Check the pilot screw. It is already drilled
    3) Change the filter out to the Uni filter or NoToil with NoToil oil.
    4) Adjustments to airbox and run it for a while to see effects of changes!

    Is the drill 7/64" drill for the slide to increase throttle response?



    thanks for the replies!
    #6
  7. Tazman

    Tazman Tazmanian devil

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    yes thats what it does.
    #7
  8. ryanwilliamcantrell

    ryanwilliamcantrell Get Out and Ride!!

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    Hey Mike,

    What are your thought on these tests?
    http://www.bigcee.com/filtertest/

    I've always thought that my K&N gave my bike better flow that the Uni ~ I use the K&N for street, and the Uni for offroad... but prefer the 'fee' of the K&N when I'm winding it up...


    Also, I never could get the Uni to seat correctly and it let a lot of dirt through to the screen... regardless of how much grease I tried to seal it with. I've never even greased the K&N and it always seal very well.
    #8
  9. eaglemike

    eaglemike Been here awhile

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    Ryan,

    That's interesting! Cary had supplied me with a lot of filter flow test info. I've seen two K&N's that had let dirt into the carb throat, too.....and heard stories of people having trouble getting them to seat. I've had no issues with the UNI. Seems like results vary.... as they say....:deal

    I guess someday I could make a couple of runs (or more) and only change the filters, and see what the sniffer says, without changing anything else.....when I get time.

    all the best,

    Mike
    #9
  10. grinder96

    grinder96 Long timer

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    Allrightythen!

    I have:
    1) shimmed the needle
    2) cleaned the Uni filter (actually already had a Uni, its the Duc that has the K&N :shog )
    3) pilot screw out 2 3/4 turns (previously at 2 1/2 turns)

    Short run last night seems to have eliminated popping to a subtle four stroke decel rumble! Going for a putt today and I will report back.

    Thanks for the input!!!
    #10
  11. grinder96

    grinder96 Long timer

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    Engine ran flawlwssly!!! It excellerates great and rumbles on decel! Thanks for the input everybody!!!!

    Turin
    #11
  12. gotadrnow

    gotadrnow Been here awhile

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    man my klr is bad for this right here just got her on the road to
    #12
  13. gotadrnow

    gotadrnow Been here awhile

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    :eek1
    #13
  14. SkiBumBrian

    SkiBumBrian DualSport Crazy !!

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    Might be a record ..... 5 year old thread!
    #14
  15. gotadrnow

    gotadrnow Been here awhile

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    i love the internet.

    well time to read over this thread today where to start?
    #15
  16. gotadrnow

    gotadrnow Been here awhile

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    is there any videos or pictures on this one guys?

    thanks
    #16