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Running Rich, stalling alot

Discussion in 'Technical and Troubleshooting Torque' started by mrp, Aug 8, 2007.

  1. I have an 89 FZR250 (recently cleaned/balanced carbs) that loves to stall when I don't rev the shit out of it. If I try to use revs below 5000, when I pull the clutch in to stop it will stall unless I blip it to like 8000 or more. I'm pretty sure it's running to rich and have been playing with the idle mix screws but havn't found the right setting yet. Can someone tell me how to adjust the needle/circlip that are in the carbs. I think I need to change that before playing with the mix screws.
    I have also heard it could be the float levels being to high which causes a fuel blockage which would give me the same symptoms. Is it simple to adjust this level?

    I've nailed it down to these two problems, also maybe needs a valve clearance since it gets such bad fuel consumption. Only get 110-120 without reserve.... but that wouldn't make it stall would it?
    any advice appreciated

  2. If you dont know how to adjust the needles of the floats,better to find someone who does as this can be quite a lot of messing around,you might set it too lean and that will cause other problems that you definatly dont want :grin:
  3. The right combination of float height and pilot screw settings will sort it out.

    Find out what the pilot (idle) screws should be set at, and leave them at that. Then adjust the float heights to where they should be.

    Needle setting will be irrelevant to the low rpm running.
  4. Your bad fuel consumption probably is because the needles are wrongly adjusted though!
  5. I can get my bike to idle evenly with just under 3 turns out on the idle mix but it will still stall. I've had it running to rich (revs drop then rise) and to lean (vice versa) with no change, although having it abit lean makes it less prone to stalling because of the rise in idle rpm. This makes me think even more that it's the floats causing the problem.
    That and I'm sure that circlip needs to go at least 1 knotch leaner. I'm quite mechanically capable and will open up the carbs (again) to have a fiddle with this weekend. The way I understand it now is changing the height of the needle makes it more/less rich?????? Can you do this with stock needles?

    thx for the replys I feel like im getting somewhere, I just need some good guidance now :LOL:

    edit: thx for the link ibast, good info there man
  6. Do you know what factory settings are and if you have factory needles and jets? If so, that is a great place to start from and work from that.

    Sorry if you have already done that :p
  7. simply speaking the needle controls the mid range mixture. Lower, leaner.

    but the main jet also controls mid range mixture, because fuel goes through the main jet to get to the needle.

    Idle mixture doesn't jsut effect idle either. It comes into play when you are on minimal throttle then crack it. Think about how often this is important to the way a bike feels.

    Are you sure you are adjusting mixture rather than idle speed?

    You have 4 idle mixture screws and 1 idle speed screw.
  8. I'm sure lol. Not all bikes have 4 mixture screws, mine has 3.
    It idle's well atm but still stalls and runs to rich.

  9. mmmmm? alarm bells ringing.

    You don't have one mixture screw per carbie?

    Are you sure you are not adjusting the balance screws that sit in the space between the 4 carbies? There's 3 of those.
  10. +1.

    The revs shouldn't rise and drop if you adjustthe pilot screws, they will if you're fiddling with the balance screws.

    First thing to do is to get a manual, you can find them online.
  11. mrp what type of fuel are you using? ULP or PULP?
  12. I can tell you what the problem is:

    The carb settings are farked.

    Return everything to the standard settings (and balance) and go from there.
  13. Well going on what cammo is saying I am adjusting the balance screws, I thought they were the idle mix screws which were different from balance/synchronizing screws? So I need to adjust the pilot screws which are INSIDE the carbs right? Behind that bit of metal you have to drill out?

    Maybe it's not just my float levels :shock:
    To many different screws and only japanese to tell you what is what :?
  14. do a carb balance again first as it's surely buggered now. Then set your idle speed.

    It may be fine without touching the mixture screws.

    If you have to the mixture screws are usually located under the carbs towards the engine, though not always. they may be covered with a "brass" plug though I doubt it as this tends to be a US thing.
  15. funnily enough my carbs don't even have any other mix screws.. no brass plug or nothin. I found the needle to be set right and fixed the float level and it runs much better now. I can tell it's leaner also.

    thx for your help guys, I'm much happier with how it runs but I have a new problem now (not as bad) with the carb piston thingy