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Lowering revs until stalling

Discussion in 'Technical and Troubleshooting Torque' started by Arjo_Savage, Oct 29, 2007.

  1. Hey there guys.. new rider here..
    Can anyone please help? My bike dies while idling in neutral, first... anytime when im not giving it some..
    progressively i hear the revs lowering and lowering until it finally gives up. this happens every single time i leave the bike idling for more than 10 seconds!
    The bike is an oldie.. 1988 kawasaki zx2r 250cc, it has done 17500 kms.
    I dont know if this is related but also when i have the choke on the revs seem to fluctuate..
    Any ideas!?

  2. carb tune/kit time!
    take it to your local mechanic and say "fix my carbies farkin!"

    also, could be:
    *blocked air filter - she needs to breath
    *blocked fuel filter
    *blocked jets
    *incorrect air/fuel ratio
    *incorrect sync of carbs
    *perforated diaphragm
    *plug leads
    *bad fuel
    *coils not producing enough spark at idle

    list is endless :!:
  3. Is the fuel that important?? i have been reading on here that optimax ie v-poswer is bad for your bike however i have been putting that in my bike.. is this a no no!?
  4. it can be, some bikes dont like it.
    run some regular through it and see if it idles better.
    the fancy fuels have additives that change the density of the fuel, therefore changing your air/fuel ratio. sometimes to the point of rough idle.
    how long have you been using the optimax for? did the issues only develop after you filled with it?

  5. :rofl:
  6. shhhh, he's learning stuff ;)
  7. be gentle Phizog :p

    maybe adjust the idle screw? sounds like a fuel supply issue though. Mechanic time...

    Personally i stay away from all shell fuels, tend to use caltex 95 and a tank of mobil 8000 every now and then
  8. maybe try a carb cleaner first (nulon total fuel system cleaner) and a good hard run. worked on my old kwaka.
  9. First thing to do is wind the idle stop screw in a little. This will get you by. It may be that it vibrated it's way out.

    Then run some carby cleaner through the tank. Maybe try one tank of E10.

    You may then find it revs to high, then you just wind it back again.

    A new set of spark plugs won't hurt, particularly if you have been playing silly buggers with the choke.

    If after you have done all that you are still having troubles, then you probably need to get the carbies off, give them a good clean. Then put them back on and they will need balancing
  10. Idle circuit.

    If you need to wind up the idle soo much that it does not stall, but then the revs drop slowly after you blip the throttle, you 100% have idle circuit problems.

    To get this right, get access to teh carbs and there should be a flat head screw in the bottom of each carb. This should be around the 2.5 turns out, but depending on other factors could be 2 or 3 or way different if you have other problems.

    Play mechanics and set them all at 2 turns out. How does it run?
    Go to 2.5. Run better?
    Go to 3? Worse?
    Once you find where it runs well, then move in 1/4 turns, down to 1/8 turns, till you get the sweet spot.

    Problem fixed. But you should also sync the carbs, clean them properly and all the rest.

    If you cant get it better, remember how many turns they were in the first place and put them back to that and sync the carbs first.
  11. Make sure your carbies are clean and synced with little wear and tear, before you start mucking with idle mixture.

    It may partially cover a problem, but will likely create others in the process.

    I'm not saying it's not a mixture problem, just that you will be chasing your tail if other things are not right first.
  12. Farkin oth!!!!

    In an ideal world. Clean all the passage ways in the carb. Make sure the slide holder is not oval, check conditions of all jets for wear rings.

    Sync carbs. Set float height.

    Dyno to get main jet, then slide, then pilot jet, then work on the idle circuit.

    Assuming you have good fuel, new plugs, good leads, etc.