YZF R125 Sprocket Gearing Table Ratio

Discussion in 'Technical Discussions' started by diasilman, Sep 26, 2009.

  1. diasilman

    diasilman Member

    YZF R125 Sprocket Gearing Table Ratio

    Hi guys, im creating here the gear ratio table for your YZF R125.
    below is the possible sprocket gearing combinations you can use in your R125
    (note some combinations may fit or not fit with your bike, please take caution)

    These are arranged by gear ratio.

    How to use this table?

    The gear ratio is the number of turns of the rear wheel it makes for one complete cycle or complete revolution of engine.
    Just imagine it in bicycle. if yo have 3.0 gear ratio,
    one full turn of foot pedal, will have 3 turns of your bicycle rear wheel.

    How to know which one is best?

    on your 6th gear, stock sprocket combi 14 48 = 3.43 gear ratio
    -if you were able to max out 10,000rpm ecu limiter
    then that means you can proceed to much lower gear ratio (see color green)
    from the table you can try 15 51 or 14 47 or much lower gear ratio
    Just experiment which one...

    -if for whatever reason you cannot maxout your rpm limiter of 10,000rpm on 6th gear,
    that means you need the higher gear ratio (see color red)
    just make sure to increase the gear ratio in step by step
    so that you will know which one works best with you.

    Why one sprocket comibination will not work with all bikes and owners?
    Because each owners have different weights, each owner have different terrain in places.
    there are lots of factors...

    Hope that helps guys,
    yours truly
  2. yamyzfr125

    yamyzfr125 Member

    you cant get rear sprockets for the r125, i have been trying too.
  3. kevshek

    kevshek Guest

    I can get a rear one cut, basically its aluminium, with the correct number of teeth nd the correct hub size. You wold just need to drill 6x 8.5mm holes to match the bolt pattern. Cost about £40.
  4. arielshah

    arielshah staff Staff Member

    Hi Kevshek u should check with afam sprocket or Renthal sprocket they do have for R125 it very light material :cool:
  5. arielshah

    arielshah staff Staff Member

    Hey! guys u all should check with Afam sprocket or Renthal they do have for R125 front n rear just name it the size they can make for u' but one thing u should order @ least more like 5pcs for front n rear thats what i heard from the Renthal distributor in s'pore :shock:
  6. kevshek

    kevshek Guest

    I tried afam a month or so ago and they did not have any listed for the r125. Do you have any part numbers? There could be a chance they could match one up if given the specs of the sprockets in my other post.
  7. Benji

    Benji Guest

    The only sprocket Renthal list is the standard one. I have got one of these and it is a fair bit lighter than the standard steel one fitted.
  8. arielshah

    arielshah staff Staff Member

    Does ur country sell this bike FZ150 fuel injection...? bcoz this bike rear sprocket have the same diameter like ours r125
    im now using it rear size 42t trust me guys by using big bore from malossi im able to reach my top end @ 146km/h @ 10rpm
    and there is another thing i should like to inform u guys top performance did sell racing cdi with no power cut which cost sing dollar $580/- check this G-MAX race web site http://www.singaporebikes.com/forums/sh ... p?t=243913
  9. easyrider63

    easyrider63 Member

    finally got my 15 tooth sprocket fitted -running 15 and 48 and god does it make a diference. will give a full report when ive been back down the coast and back. :cool:

  10. hi guys, so what do you think what is the best combo? and did i understand well, bigger ratio is better?

  11. Hi All
    very interested in this 1, my yzf wont get any wear near the redline in 6th,
    Dont know why.
    I have looked on the net for a sprocket with less teeth to improve top end, sadly not found 1 could anybody point me in the right direction please, and also how many teeth on the sprocket would be good for me,
    i can get to about 6-7rpm in 6th.
    Many Thanks
    in advance
  12. Benji

    Benji Guest

    You need to be taking it to 10,000 - 10,500 in 5th before changing to 6th.

  13. so what this chart says is if you have a front at 16 n rear at 43 your bike should be hitting the 100mph mark? wouldnt this be too much pressure on a little 125 cylinder or would it be ok?
  14. MikasPT

    MikasPT staff Staff Member

    that's correct with 16 front and 43 rear 100mph, but the motor don't have the power to get there, that numbers indicate the limit of physical speed of the transmission.

  15. so in order to acheive the 100mph mark or above id need to invest in the malossi kit?

  16. So with a malossi kit and a 16 front and 43 rear on paper it will hit the big 100? i didn't think the kit had that much power.
  17. arielshah

    arielshah staff Staff Member

    sory mate if my speed was @ this 147km/h what is the convesion of the mp/h...? just asking

  18. that's about 91mph mate. ;)
  19. arielshah

    arielshah staff Staff Member

    thks mate for the information
    but one thinks that i'm quite confused being trying quiet few time to reset the meter from km/h to mp/h but seem it didn't work at all as i already follow the instruction manual press the reset button for 8 second..... :?
  20. Benji

    Benji Guest

    I don't think every country had this option, I know the UK bikes do.

Share This Page