YZF R125 Sprocket Gearing Table Ratio

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

  1. bit of help here guys??

    i want more acceleration!!! not to fussed about top end as i ride in london and very rarely even go on A roads.

    i guess by dropping down to 13T on the front that should help? is it feasable to go lower/ say 12 for MORE acceleration?

    or what about changing the rear instaed of front? i would think changing the rear to get the same effct would be better cause of less weight and rotating mas ect?

    what would you guys recomend/ has anyone tried for more acceleration (ie using a 13T)rather than top end which is what most seem to be trying for?

  2. Ok, i've populated most, not sure on primary drive or change up and change down rpm,

  3. MikasPT

    MikasPT staff Staff Member

    no, the only way to get 100mph/160.93 km/h is a 17 T Front Sprocket or 16T Front and 45 T rear or in the case of the new kit of malossi 15t Front and original rear 48 if the rpm limit change to 12k rpm them you can go to 100.4 mph.
    let me explain a little more the new malossi kit have a second generation of electronic box and they can change the rpm limiter, they guaranty more 1k rpm but they say in some models of this motorcycle that limit can go to 1500 rpm more so if you have the right model of the yzf r125 the red line can go to 12 k rpm with 15 t front you can hit the 100 mph mark, just a little before motor make bumm, because afther 11k rpm the valves are floating. only hidralic valves can work at higher rpm just like yamaha r6 18500 rpm red line.
    or you can sell your 4t motorcycle and buy a 2T 125cc motorcycle restrict in documents to 15cv ( 11kw ), and you get a 125cc motorcycle with 30cv or more and you can pass 100mph, but remember what you want and why do you buy this model, i think you have to find yourself before do any mod, because a person that buy a good economic very good looking motorcycle but want to ride the motorcycle to 100mph he don't know what he want.
    sorry about my english and sorry this text is not to hit you just my opinion.

  4. has any1 encountered a problem with 15T front + 48T rear on a fully stock bike?

    will the bike still reach a better top end?

  5. anyone?
  6. Benji

    Benji Guest

    Sorry had missed this one, it has been discussed in other threads, the answer is yes it would be faster if the stock engine had enough power to push it, most people have found they change back to the 14 front and 48 rear, sixth is just too much of a jump from fifth, leaving the engine in the wrong place on the torque curve to be able to get on top of the gear.

  7. Thanks Benji

    been goin through the other threads but wasn't really able to find a conclusion to the topic...

    have you noticed any difference from the 2008 models to the 2009/10?

    been looking around and it seems the 2008 is able to reach 135km/hr easily while the 2009/10 has trouble reaching 120km/hr..

    was considering a sprocket change to compensate for the performance, but from what it looks like, the only solution is a 150/183cc kit + powercom..

    any other solutions that you can recommend?

  8. If I change sprocket from 14 to 15, do I need to change also the chain. Is then to short or I can have original size 134?
  9. L-J-P

    L-J-P staff Staff Member

    Re: YZF YZFR125 Sprocket Gearing Table Ratio

    I think you can just use the sam chain! Correct me if i'm wrong people!
  10. YZFDanR125

    YZFDanR125 Member

    Re: YZF YZFR125 Sprocket Gearing Table Ratio

    Yup same chain ;)

  11. [quoI"mark j, post: 2355, member: 1033"]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[/quote]
    Hi mark, I've got the same issue my yzf won't go near the red line in 6th gear just wondered if you now a solution to this?

  12. So, for more top speed, I should increase or decrease gear ratio?

  13. in theory decreasing the gear ratio will result more top speed, but if the engine horse power isn't enough in high rpm, it will struggle to reach the the top speed.

  14. At this time, i can i hit the rev limiter in 6th gear easy. After installing a 150cc cylinder kit and a stage 2 camshaft, i think i'll be able to decrease just a bit the gear ratio, right?

  15. Yes.

  16. Deleted.

  17. Deleted.

  18. Deleted.
    Sorry again...

  19. Good :) Is there any way to estimate the top speed by changing gear ratio?

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