Yamaha DTR 125 CDI unit Questions



  • Hi there

    im asking on behalf of a freind.

    on his bike he has a cdi unit that has no numbers or writing on it and we have a feeling its restricting the bike

    It will fly up to 60mph but it will not rev past 8000rpm when the bikes moving but if he is sat in neautral and opens the throttle full it will rev to 12000rpm is there any chance this could be the CDI unit?

    It has the YPVS System set up and a full dep system along with carbon fiber Reed's

    there is no green or black wire and there is no reed switch as the wiring loom isnt in that year where they had reed switches

    we dont know exactly what year the wiring loom is as it was swaped by the previous owners but they think it was a 1995-1996 loom, the bike its self is a 1988 but registered in 1989.... Any help on this would be fantastic... if you need more info please ask and ill get the info you need.



  • Pin the valve and try again. Sounds like the YPVS is retarding and limiting that upper power.



  • Cheers calum! we have tried this and makes no difference...



  • Possible reed switch related then.

    Otherwise the CDI could be going faulty.



  • @Calum cheers calum, the bike has no reed switch on the loom no signs of the wires anywere, on my own dtr which is a 2002 my wiring loom isnt the same so this is why we are struggling as we have nawt to compare it too, and we cant compare it in the haynes manual as the wiring loom has been repaird due to old rotten wires etc... so im thinking it the CDI limiting the RPM but i wanted to get a second opinion



  • Could be any number of reasons.

    Is the engine worn. Clutch worn out?

    Is the powervalve actually operating correctly, I.E. are you pining it in the open position.



  • Does the bike have the round slide or flat slide carb? Looms differ markedly over the first 2 years and early looms have separate ignition control relay from cdi.


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