Transmission issue after changing sprocket

Discussion in 'The Garage' started by Zniper, Oct 5, 2018.

  1. Zniper

    Zniper Adventurer

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    Hi all, I've just had the front sprocket change to my KLX250 and now feeling terribly nervous. It has these issues:
    - With center stand, in neutral, the tear wheel spins extremely fast (I know how it used to spin, quite gently)
    - I likely can't spin the the output shaft by hand (while I can before). Hence, heavier to walk the bike.
    - It's harder to shift and sounds noisy.

    I saw the mechanic hitted the cover lock nut on output shaft with a hammer before using air impact wrench, and guessed that caused the problems above (my bad, I didn't stop him :( ).

    So, what could possibly the problems with the bike, and should I continue to run and watch it or tear it apart for inspection? The bike only has 200km on it :-(
    #1
  2. oldmanb777

    oldmanb777 Just say NO to socialism! It's a bad drug!

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    I'm not familiar with the KLX250. but my DRZ400 (and some others I have owned) have a lock washer that locks to sprocket nut in place. You would need to use a hammer and some sort of drift to bend the washer away from the nut, before removing the nut.
    Since your bike is new, I assume its still under warrantee. I would take it back to the shop, and have them make sure its is ok. No problem asking when you don't know.
    #2
  3. Project84

    Project84 I can haz adventure?

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    With the information give, my best guess is the chain sounds too tight.
    #3
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  4. Zniper

    Zniper Adventurer

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    Yeah right, it's similar with the washer, I've already bent it out before.
    Per warranty, they mentioned that it won't be covered as they didn't make that installation, and surely it will takes a lot time with the procedures.

    Thanks, however the chain slack is still within specs. I've got that opened/adjusted 3 times today.
    #4
  5. oldmanb777

    oldmanb777 Just say NO to socialism! It's a bad drug!

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    You need a second person to look at it before you go any further. Hopefully you have a riding buddy to give a second opinion
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  6. Beezer

    Beezer Long timer Supporter

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    you say "can't spin the the output shaft by hand (while I can before). "..... is that with the chain off? if so, thats bad.

    otherwise, I'll go with chain is too tight
    #6
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  7. Yooper_Bob

    Yooper_Bob Insert witty saying here....

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    Was the rear brake or the transmission used to hold the output shaft in place while the "mechanic" used the impact wrench to loosen the nut?
    #7
  8. Smopho

    Smopho Been here awhile

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    T hey may have put heavier oil in it than what is required and that is causing the clutch to drag more than it did before.
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  9. south

    south Long timer

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    I initially thought "clutch" as well, until I recalled the OP stated the issue occurred when in neutral, which rules out any clutch issue.

    Working under the assumptions that 1) you're not comfortable with undertaking the diagnosis/repair job yourself (in light of having someone else perform the sprocket swap), and 2) you're (understandably) not comfortable having the individual who performed the sprocket swap undertake the job, I personally would take the bike to a dealer--other than the one you've already spoken to and provided the backstory to--and simply play dumb: don't mention anything about the sprocket swap; just tell them what the symptoms are and that you just recently noticed the issue--when you were cleaning/adjusting the chain or whatever. Treat it as a spontaneous issue/obvious warranty claim. They'll do the diagnostic work, and if they fix it under warranty, great; if not, worst case, you have them put it back together and you take the bike back, now knowing what's wrong with it. And with a disputed warranty issue like that, should be a good chance they won't charge for the diagnostic work, even if it requires you to make a bit of a fuss to make that happen.
    #9
  10. Zniper

    Zniper Adventurer

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    Agreed. I already visited another professional mechanic, he didn't know for sure if that's the clutch or transmission related. The advice is riding it some more and see if something changed, or at least over the break-in period. He admitted that he doesn't want to tear it apart or even open the clutch side cover.
    Yep, I have the chain in place and rear break applied while doing that (and that with the hammer :p)
    I concerned about it (possible dragging clutch) and already replaced with an semi-synthetic one (Liqui Moly 10W40 street, used that brand once) but the issue persists.
    Really nice thought and advice, I played part of it when bringing my Kawi to the dealer yesterday. After 2 hours, their conclusion was rear wheel bearings, and while they were planning to make the video and send it to HQ with mentioning about days/weeks to get the bearings and replaced. I gave up and went to another professional mechanic mentioned above.

    Thank you all for the replies and ideas! I'm now preparing myself to accept the fact about a surgery (ouch!) after few hundreds kilometers.
    #10
  11. ohgood

    ohgood Just givver tha berries !!!

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    pull the nut off and reinstall it, use a torque wrench to apply the correct torque value. I'm being the mechanic over tightened the nut and it's putting station/pressure on the output shaft /transmission/bearings.

    it's very common in drz, and very easy to fix if caught in time before damage occurs.

    the output shaft should be difficult to spin when in gear, clutch disengaged (lever pulled) , and no chain, if the engine is cold. if the engine is hot will be a little easier, but nothing like neutral. it's drag from the oil between the steel/fiber plattes on the clutch.
    #11
  12. Beezer

    Beezer Long timer Supporter

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    what he said. check rotation with the chain off
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  13. kenny robert

    kenny robert Long timer

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    there is no way for the sprocket nut to anything other than secure the output shaft to the sprocket seal spacer and inner race
    there isnt a motorcycle on the planet that gets a tight bearing from overtorqueing the sprocket nut,in fact it is impossible
    it is simply a single row radial ball bearing
    #13
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  14. ohgood

    ohgood Just givver tha berries !!!

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    i wish you were right, but unfortunately I've seen it first hand. over tightened the nut and couldn't shift. torqued to proper and it's been fine for several thousand miles.

    watched a few other people do it on both brand new and very well used drzs.

    haven't seen it on other bikes yet
    #14
  15. Zniper

    Zniper Adventurer

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    Many thanks for the advice!
    I believe it happens for some with over tightened nut and I did open and retighten that nut several times with both impact and torque wrenches under proper force. Unfortunately, it's still not my case.
    #15
  16. ohgood

    ohgood Just givver tha berries !!!

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    that's a good thing then, it means you don't have damaged bushings/bearings. :-)
    #16