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throttle body modification in fuel injected models

Discussion in 'Modifications and Projects' at netrider.net.au started by dgmeister, Mar 22, 2013.

  1. on my fuel injected R6 there is a throttle body much in the same setup as a CV carburettor
    ie, CV carburettor slide, spring, (but without a jet needle and needle jet.)

    CV carbs are rather easy to modify, i am wondering has anyone on netrider done this with FI bikes???

    shortening the return spring, putting in different slides and generally getting the slide to open faster, or even holding it open somehow, the better performance you will get
  2. Sounds weird. All the throttle bodies I've seen (and I'll admit that doesn't include modern Jap bikes) have been basically just a tube with a butterfly in it and an injector downstream. Never seen a slide.
    • Like Like x 1
  3. here is one possible modification of this type:
    lengths of aluminium pipe acting as retainers to hold the slides fully open
    this modification would have a large effect on performance,
    more impact than ANY other mods


    before with slides closed

    after mods with slides open
  4. I seriously doubt it.

    But more induction noise will make it seem that way.
  5. Do your FI bodies have the butterfly vales still? If not, you'll just make a permanent WOT mod ;)

    All you are doing it taking the vacuum slides out of the equation & the throttle butterflys are now directly controlling the airflow, without the lag before the vacuum lifts the slides.

    I doubt the power output will change, but throttle response should be better....

    I am suprised a FI bike has vacuum slide though... Wonder why Yamaha put them in?

    Edit: Looks like the injector pressure may also be increased when the slides are fully open, that's interesting.
  6. From the user luke geis on the R6 forum link you posted:

    That makes sense.
  7. Common practice in automotive applications is to bore the throttle body and use a larger butterfly. This just increase air flow but you also need air speed.
    If you want more performance, sell it and buy an R1.
    • Like Like x 1
  8. Because Yamaha have form at putting pointless shit in their induction tracts. YICS anyone?
  9. yes, max power will not be increased (as the slides would be open anyway)
    BUT response will, and that is all that matters when you already have 100hp

    CV slides smooth out power delivery by waiting for the engine revs to rise and suck in the fuel before the slides are opened, sort of like having asthma in a running race.

    in all areas other than 100% throttle there will be more power,
    and better response, especially important on a 600 to get some more mid range response and less restriction

    other mods would retain the slide configuration, but allow the slides to open faster by increasing vacuum effect or shortening the return spring, or holding the slides slightly open (rather than fully open)

    ??????Is a regular EFI set up on a competitor sportbike just the same as the second pic??????????
    ie; butterfly exposed, and butterfly only (no slides etc)
  10. this is not an 'addition' mod, it just removes RESTRICTIONS,
    to make the engine perform how it should

    modifying a CV carb in the same vein will give large returns.

    NO - top end power is not increased, BUT you get to full power 10X faster, so you actually do get more power
  11. chances are these might be on R1's aswell

    remember these slides effectively restrict your intake, in order to have smoother response

    If you are trying to get more power for relatively no outlay,
    this would be one place to look