TTR125 piston cylinder help

Discussion in 'Mini Racing' started by Daniel06, Feb 5, 2013.

  1. Daniel06

    Daniel06 Well-Known Member

    Alright. I have a ttr125. Since I bought it, it's had an engine tick a idle and low lugging rpm's. Up top range rpms it runs great. So I tore the engine down and found that the piston to cylinder clearance is .0045
    The manual says to have around .0008-.001 inch or something like that. It also states that .006 inch is the limit. I'm pretty sure the tick is piston slap. I didn't find anything else this far.

    Bike ran great except for the ticking. It's not the valve adjustment either. That's been checked and rechecked.

    Thoughts? .0045 too loose?

    I'm thinking I'm gonna put a 1mm over piston in it. Anyone have a good source for a piston kit? Also, I'm in Birmingham, AL. Anyone know a good local shop to do the bore for me?
    Or, does anyone have some parts laying around that I could buy?
  2. gluvnaa

    gluvnaa Well-Known Member


    What are you going to do with the bike? Play or mini race?

  3. TurboBlew

    TurboBlew Registers Abusers

    on one of mine I did the 1mm over. Local guy did the bore for ~$40. The piston/ring/pin was a wiesco and it was like $55 shipped.
  4. Daniel06

    Daniel06 Well-Known Member

    Just ride the shit out of it. Not Planning on any of the class racing. Just a little trainer.
    If I thought it would stay together, I'd just put it back together and ride the hell out of it.

    .0045 clearance and piston slap, detrimental?
  5. RM Racing

    RM Racing Tool user

    On that little piston, that's a lot. As TurboBlue says, really cheap to fix.
  6. Daniel06

    Daniel06 Well-Known Member

    Cool guys. I'll order the weisco kit and just have it punched out. It seems the cheapest route since it comes w/ new pin and rings.
  7. bella749

    bella749 Well-Known Member

    FWIW, my TTR ticks like that too. I'd just ride it.
  8. bruceiam

    bruceiam Well-Known Member

    Mine makes noise at all rpm, I've been waiting for it to come apart for 3 years....
  9. kz2zx

    kz2zx zx2gsxr

    I don't know if mine makes noise or not... I think I need to ride it again.
  10. backcountryme

    backcountryme Word to your mother.

  11. Daniel06

    Daniel06 Well-Known Member

  12. defiant900

    defiant900 Well-Known Member

    Is that an aftermarket forged piston or the stock cast one? I am pretty sure the Wiseco forged pistons run much larger clearances than the stockers. Around .0035 in to .0045 in. They will tick more when they are cold.
  13. Daniel06

    Daniel06 Well-Known Member

    Its the stock Yamaha piston and cylinder. It ticks cold or hot at idle and when lugging. Wfo it sounds smooth.
  14. Tdub

    Tdub Say what???

    For this size motor the Wiseco only needs an additional .0005" to .0001" more than a cast piston. .0035> is too much for this motor.
  15. defiant900

    defiant900 Well-Known Member

    Yeah, you are probably right. That is just what the Wiseco rep told me to run for the 11:1 Forged Wiseco piston on my ttr125. Maybe someone else set his bike bike up with a forged piston at .0045 in, perhaps.
    Last edited: Feb 8, 2013
  16. Daniel06

    Daniel06 Well-Known Member

    No worries. Imma fix it right. It's a stock piston that is either wore out or setup loose. Either way, I've got it apart, I'm gonna fix it. Thanks for all the inputs.
  17. backcountryme

    backcountryme Word to your mother.

    Just big bore it. Everyone needs more power.

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