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GSF250 revs etc.

Discussion in 'Technical and Troubleshooting Torque' started by Envy-t, Jun 26, 2008.

  1. Another question from me!

    When I am taking off, and give the bike a few revs, if for any reason I need to stop suddenly, the revs drop and it stalls. If I am sitting in neutral, the idle is happy at about 12-1500 rpm, but if I twist the throttle a little and back off, it almost stalls, but then idle is now almost half.

    I also notice that sometimes when taking off, the bike will have nothing and stall. When this happens, I can twist the throttle all the way and nothing happens for a few secs. The only way to catch it before stalling is to quickly rev on/off/on/off etc while the clutch is in.

    Please help!

  2. Carbs could be out of balance. When was the last service on the carbs?
  3. Good Question.

    I might book it in for a service. i have only owned the bike for a month. Hav replaced the chain and sprockets for good measure, will do service next.
  4. there's a thumb wheel on the left hand side (when sitting on the bike), that is attached to the end of a cable, that runs up to the carbies, this is the idle speed adjustment.

    with the bike warmed up and idling, wind this to increase the idle speed to 1800-2000rpm at the most. sounds to me like your motor is idling WAY too slow at 1200-1500rpm. stock idle speed is 1600rpm

    i've not played with the carbs on my Bandit, as there's been no need to, but i'd suggest getting yours balanced and tuned to make sure it's getting the correct mixtures.

    sorry i cant help much more, i'm an EFI kind of person.
  5. +1 sheppo.

    these small 4s idle a bit higher than this.

    If it's still got the problem after the idle speed adjustment, it could need an idle mixture adjustment. the following is advise on adjusting the idle mixture screw.

    A rich problem gets worse as the engine heats up.
    o If the throttle is lightly "blipped" at idle, and the rpm drops below the set idle speed, then rises up to the set idle speed, the low speed mixture screws are probably set too rich: try 1/2 turn in, to lean the idle mixture.
    A lean problem gets better as the engine heats up.
    o If the throttle is lightly "blipped" at idle, and the rpm "hangs up" before dropping to the set idle speed, and there are no intake leaks and the idle speed is set at less than 1000 rpm, the mixture screws are probably too lean: try 1/2 turn out, to richen mixture. Be sure there are no intake leaks and the idle speed is set at less than 1000 rpm!
  6. I have got DREW from rolling moto repairs coming out today. Service and tune up.

    Thanks for the replies people, this place is great!
  7. Bloody backyard mechanics!
    While Drew was working on the bike we found why the above problem was occurring. The previous owner has replaced the choke cable with one that is too short and therefore extended it with a peice of wire and tied it around the choke slider. So every second time I use the choke, then shut it off, it doesn't close fully, leading to a massive flood of fuel and the stalling and subsequent hard starting.

    No1 and No4 Carbs were out of wack too.
  8. HAve you ridden it since it's been serviced?
  9. Yep, and it feels like I have picked up the 10 odd horsepower that I didn't have when I bought the bike!
  10. Feels like a joy in comparison I imagine - nice one :)