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749 Not Reving Out

Discussion in '749 / 999' started by Spjallen, Mar 25, 2017.

  1. Hi Guys. I'm down at Ty Croes race track with the 749 and it won't Rev out, struggling past 7000. Any thoughts? It sounds rough as when trying to rev out and occasionally will go to 8500 but no more, and it is occasionallly. I'm not running a power commander either, just a flashed ecu. Changed the plugs and coils too.
     
    #1 Spjallen, Mar 25, 2017
  2. Check fuel lines in tank. With fullish tank watch through cap while pump primes. Air bubbles mean leak. Possible clogged filter also. When was it last changed?
     
    #2 900streetfighter, Mar 25, 2017
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  3. thank you. Changing the filter as I type.
     
    #3 Spjallen, Mar 25, 2017
  4. Use metal cased filter. Plastic can split with hp on inj systems.
     
    #4 900streetfighter, Mar 25, 2017
  5. I've had similar problems with my 998, which is also a Testastretta engine. Mine was the air gap on the pickup sensor.

    On the road it always seemed fine but as soon as I hit the track it was holding back. Probably not much you can do to fix it as you will need some some shims to set the gap correctly, if that turns out to be the problem.
     
    #5 Red998, Mar 25, 2017
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  6. If the gap is too big, you can take out shims, rather than add them.

    Sounds like water in fuel to me.
     
    #6 ducati dad, Mar 25, 2017
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  7. damp front coil??
     
    #7 Old rider, Mar 25, 2017
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  8. Relay.
     
    #8 RickyX, Mar 25, 2017
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  9. Changed the filter. No improvement. Thanks anyway.
     
    #9 Spjallen, Mar 25, 2017
  10. Good shout with the front coil, but changing that, and the rear didnt sort it either.
     
    #10 Spjallen, Mar 25, 2017
    Last edited: Mar 26, 2017
  11. Brand new relay. Changed it anyway but no luck.
     
    #11 Spjallen, Mar 25, 2017
  12. Thank you for the water in the fuel idea. Changed all the fuel to brand new and fresh. No joy.
     
    #12 Spjallen, Mar 25, 2017
  13. plug breaking down?

    Got a PC fitted? Have seen quite a few of those fail.
     
    #13 bradders, Mar 25, 2017
    • Like Like x 1
  14. #14 Spjallen, Mar 25, 2017
  15. I'm changing the fuel pump next with dyno time booked for the weekend. I'll let you know how I get on
     
    #15 Spjallen, Mar 30, 2017
  16. seems my 749 is fixed Gents and a recent dyno run confirmed it. I changed quite a few bit with the problem being the fuel pump and it strainer. Pump pressure was increased so much I had to change the fuel pipe connection. A word of causation though, buy the correct pump, not all the ones on eBay fit your fuel plate. Buy one that's oem
     
    #16 Spjallen, Apr 23, 2017
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  17. Good news :)
     
    #17 Old rider, Apr 24, 2017
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  18. I've changed quite a few pumps over the last year, petrol isn't what it used to be and the more ethanol and additives the add they worse it gets for the old fuel systems.

    Plus it rots the internal fuel and breather pipes out..
     
    #18 KeithMac, Apr 24, 2017
    • Like Like x 1
  19. I think classic bikes struggle with it too. They generally drain all the fuel as it rots the tanks!
     
    #19 Spjallen, Apr 24, 2017
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