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I think it's my shift star...

Discussion in 'Mechanical & Technical' started by Heavy-T, Apr 21, 2011.

  1. To all of those that may have dealt with this...

    I have an 04' KLX 300 that seems to find neutral more than I'd like. It works perfectly fine if I have the revs just right and gear it up or down but when I grab the clutch under any decent speed VROOOOOOM and I'm coasting... it kind of takes the wind out of my sails.

    I've read around and am thinking that I need to modify my Shifter Star. Has any one of my fellow riders tried this?

    I read this site and multiple others giving advice and they say it works. But me being the type of guy I am, I don't want to tear into something if I'm not sure it's going to work.

    I have a very keen mechanical prowess but I'd still like to talk to someone that may have done this or may be willing to assist me either hands on or with words of encouragement and pointers.

    I has beer

  2. PeteN95

    PeteN95 Moderator Staff Member

    I'm not sure I understand the problem? When you "grab the clutch", you should be coasting becasue that will disconnect the engine and transmission. Do you mean that it will pop out of gear when you pull the clutch lever? Are you slipping the clutch to get more rpm?
  3. Sorry I explained it so horribly, it did sound like I was holding the clutch in by my previous explaination... I've been riding motorcycles for 11 years so of course I know that I coast when the clutch is in :tard:

    I meant to say that at high speeds when I use the clutch to shift, as soon as I release the clutch and roll the throttle on it revs like it's in neutral (even though I'm shifting from 3rd to 4th.) When I do a clutch free shift I don't seem to have that problem (but I don't like doing clutch free shifts at higher speeds) It doesn't happen all the time but it seems to do it more when I actually need the power, climbing a hill, speeding up for a jump.

    Let's assume it isn't user error as I have never blown a trans or had shifting problems on any bike I’ve ever ridden (until this one).
  4. Does it stay in "neutral" until you shift again or does it just hang for a second or two?

    Have you checked the clutch springs?
  5. sounds to me like you need to make sure you have some slack in your clutch cable.

    if that's adjusted properly, it sounds like you'll need a new clutch.

    can you slam the gas and have it slip like that?
  6. It does not slip any what-so-ever... and when it hits the false neutral it stays there until I shift it up or down, typically down since my momentum is lost. The clutch cable is spot on from my inspection.

    When I looked into it the KLX in particular has a problem with the shift star design as it is much more rounded compared to other shift stars I’ve seen. I guess they get caught up on the "humps" instead of dropping into the valley... (if that makes any sense)

    Here is a pic of the stock shift star compared to one after the mod... the stock is on the RIGHT
    Last edited: Apr 21, 2011
  7. Well if the problem you're describing isn't the clutch, I can't see how it would hurt to try the fix. I think I'd opt for trying to replace that tension arm spring first though. Sounds like it's probably lack of tension on the gear, and not the gear itself at fault.
  8. I'll be replacing that too while I'm in there... I just don't see a reason to tear it apart, replace the spring and get the same issue once it's back together. So I figured I'd do them both at the same time.

    Has anybody done this is what I'm wondering...
  9. Hey man, i had a problem on my kx500. the damn thing would NOT shift into 3rd gear. turned out that the shift arm was bent and cracked. the bent part was hitting other stuff, preventing an upshift. that doesn't sound like YOUR problem, but another thing i found in mine was that the spring that automatically returns the shifter back to the between gears position was bent to shit. Anyways, that could be a problem.......
  10. Your shift star needs to have positive detents in it or the gears will walk on the shafts. Do not modify the shape of them. If you are looking for smoother shifting, Highly polishing the detent arm and the star helps. Most of the time the real issues are with the actual ratchet not the star.

    The engineers are smarter than the internet. If the bike does not shift properly, it is probably because of another issue not your shift detent.

    FYI they all look like that for the most part. Most false neutrals are caused by user error or bent shift forks or the engagement dogs of the gears not meshing right. Keep in mind that motorcycle transmissions are not synchronized. In fact they are mini slam boxes. If you shift gears at the time that two meshing gears have their engagement dogs perfectly lined up with each other, they may bounce off each other instead of meshing. Instant false neutral.

    I can see where reshaping them can help, but the most important thing would be to make sure there is positive stopping of the detent arm in its pocket with no rotational walking. Making them too shallow like seen in the picture is a recipe for troubles later.

    Yes I have done this. No not to a KLX and no it surely did not look like that when I was done. Round off sharp edges only, polish the shit out of it and do not modify the shape of the detent pocket. No need to bother whit preloading the detent arm spring if done right. Preloading the spring for more pressure is a band aid for poorly reshaped stars.
    Heavy-T likes this.
  11. I did exactly as you said and it shifts like a champ now! Thank you so much! It was alot less work than I initially thought it would be, I just rounded sharp edges and "polished the shit out of it" and she shifts like new!


    Rep headed your way!

  12. Shift mechanisms are very sensitive to friction as it relates to the shift drum rotation.

    Add it all up:
    detent arm roller on the surface of the peaks and valleys of the "star"
    detent arm roller bushing rotational friction on the detent arm rivet
    friction from the drum rotating in the cases.
    friction from the shift forks sliding on the shift drum
    friction from the shift forks sliding the gears on the transmission shafts
    Any friction you have - is not such a good thing. Less is better.

    Shift mechanisms are sensitive to the amount of pressure the detent arm pushes on the particular shape of the "star" peaks and valleys.

    But - the more pressure on the detent arm, the more friction in the rolling components. And the more foot pressure required to shift.

    So - to eliminate some friction by polishing is a cost effective move in the right direction.

    I usually do a polish and an arm from Factory Pro with a bearing on it.

    So - I think that Factory Pro has a klx250 / 300 micrbearing'ed arm.

  13. You created an account to post an answer to something that was resolved over a YEAR AND A HALF AGO?!?! I'm thinking you work for Factory Pro... :scratchea
  14. Dr. E

    Dr. E Theoretical Propagandist

    He was taken back by your soliloquy and felt the need to be part of this wonderfully dead thread! Newbs...they never look at the date...
  15. What did I do wrong?

  16. You revived a thread where the OP had already fixed his problem and STATED that he did... You also decided to make that your first post...
  17. Did you learn anything from my post?

  18. don't worry. it's not his brain that's heavy...if you know what I mean.
  19. Whether or not I learned anything or not is not the point, you don't bump an old that was solved a long time ago :angry7:
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