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Slash Cut-Fuel Injected bike. Possible Problems?

Discussion in 'Modifications and Projects' started by chrissybenn, Oct 23, 2009.

  1. im riding an 07 cbr125r at the moment and ive been thinking about going the slash cut on the exhaust. ive seen a cbr250rr with the slash cut and it sounded great, loud but great and was contemplating doing it to the cbr125r.
    am i asking for problems with the fuel injection? relatively new to bikes and all that just after some opinions not flamage for riding the 125 lol.
    look forward to hearing some responses.

  2. fuel injected bike means it has a pre-programmed fuel map that runs of throttle position and rpm (generally speaking). that means for any given rpm, and at any amount of throttle, the computer knows how much fuel to inject into the motor.

    if you change the air flow through the motor, with different air intake, exhaust, camshafts, etc, the fuel mapping **might** be incorrect.

    the ONLY way to know, is to put the bike on the dyno, and have the air-fuel ratio checked with the new exhaust. if it is out significantly, you'll need the mapping altered.

    to alter the mapping you'll need to fit something along the lines of a power commander, or similar.

    there you have it. go buy the pipe, and get it dyno'd.
  3. ...if you think it is worth it for the CBR125.

    Chances are it'll be fine but you don't know.
  4. No. Save your buckazoids.
  5. Most fuel injection are limited closed loop. i.e. it will adjust to changes within limits.

    Once the change is too big you need to crack the software and adjust.

    It is my understanding that this is difficult with Honda's (someone tell me if this is wrong).

    Also Honda's tend to be less tolerant to change.

    Chances are a slip on won't upset things too much, but there is still a risk.

    Usually the muffler supplier can advise.
  6. the only way to know, is to get it on a dyno and log the air fuel ratios.
  7. I agree.
    Whether or not you need a retune depends on, among other things, how much you change the back pressure of the exhaust.

    But why bother on a 125?
  8. Lots more noise and the added bonus of 126 performance, go for it.