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Gotta be running waaaaay too rich

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by Takis, Aug 9, 2007.

  1. So I've got my pretty little Across and it sure is fun but I swear I'm supposed to be getting more than 120kms out of a tank...I don't think I'm riding it hard - I usually cruise somewhere between 7 and 10k RPM which must be okay given that if I'm going 100, 6th gear will leave me about 10-11K.

    I've been Googling myself silly and figure http://au.geocities.com/ozcross250/runsrich.html is the best bet to begin with, but they talk about adjusting needles. Where are these magical needles? It's a 95 model with 80,000 on the clock (heaps, but it made it cheap).

    Does anyone have any other ideas?
  2. Tune the bike up first.
    Things that could cause excessive fuel consumption:
    Clogged air filter
    Weak spark
    Carb float levels out
    Needles and seats sticking
    Someone already messed with carbs and screwed up
    Dragging brakes

    You need to pull the spark plugs and take a photo and post it up so we can confirm richness, then you have to get the cause fixed.
    Don't modify stuff till your bike is tuned up properly, you're just wasting your money.

    Regards, Andrew.
  3. +1

    and with that many k's your needle jets are probably worn (not just needles) and need replacing. You'll never get it tuned right whilst they are worn.

    the would have wanted to be beggucking cheap justify the money you are going to have to pump into this thing.

    You are going to have to learn to do the work yourself to make it worthwhile.
  4. hey Takis i've got an across as well and similiarly gettin low 100's out of a tank, difference being mines done about 50,000k's less. took it to mick hone for a service awhile back and told them of the poor fuel economy and the mechanics note they gave me in response was to "rev it harder, they don't like to be babied"..........never taking it back there again and the fuel economy didnt get any better afterwards..
    bought some new throttle slide holders the other day so i'll chuck them in soon and see what happens

    on another note, would anyone have an idea of why my bike would be stalling if the clutch is in and i come to a quick(ish) stop? it's really quite dangerous :shock:
  5. You're dropping the revs too fast, dont let the clutch out so early perhaps? But yes, the Across do need to be revved. Don't bother sitting any lower than 7k, mind you don't bother winding them out past 11k either, not much more happens past 10.
  6. Way to kill my beautiful dreams. :grin: Well it was less than 2 grand and I only plan on keeping it till I can upgrade so if it costs more than a year's worth of extra fuel (about a grand) I agree, not sure if it's really justified. But it'd be nice for the next guy not to have the same problem.
    Heh was just looking at the online copy of the manual. Pages 2-7 and 2-8 (the spark plug pages) are missing! Erk. How do I get them out?

    @andy: awesome - no offence but I'm glad someone else is my situation. :grin: Let us know how you go!
  7. Just noticed you posted the no choke post, these two are related problems.
    You also have to worry about greatly reducing your engine's lifespan if running very rick, and part throttle riding will not be nearly as enjoyable as it could be.
    I would strongly recommend having the carbs rebuilt at this time.
    Or, perhaps your choke is stuck on? I just thought about that one, check your workshop manual and adjust it as per the instructions.

    Regards, Andrew.
  8. Sorry mate. Just emphasizing the fact that you'll need to learn how to spin a spanner. Still it'll be a good opportunity to learn and that what first bikes are about.

    Andy; try adjusting your side stand kill switch. Sometimes the side stand flops a bit under heavy braking. Also my first bike used to do this when the tank was less than 1/3 full. So think about that too.
  9. Spark plugs - replaced.

    No choice there, it didn't start this morning. Never had a problem before, but today it would turn and turn and turn but wouldn't fire. Pulled the plugs et voila:


    It's a bit hard to see cause it was really bright today, but basically all four plugs were black as. Replaced them and engine caught first time. I'll watch my fuel usage now and get back in a couple of days.

    According to http://au.geocities.com/ozcross250/SparkPlugs.html, a shiny black plug (as all four were) is caused by oil leaking into the cylinder, and is also categorised by blue smoke. I'm pretty sure my smoke is colourless, I never see anything, at least while the bike is stationary, so I'm not revving but'd expect to see something.
  10. This, and your fouled plugs, could point to the idle screws (pilot screws) being in need of adjustment. A carb balance probably also wouldn't go astray if you don't know when it was last done.

    Another possibility is that your needles are worn, especially at that mileage.
  11. Get the carbs set up a bit better before you go looking for oil leeks. chances are you are just drowning the plugs.

    What was the engine doing when you last stopped it? Idling for a bit?

    You can check compression and this should confirm any more serious damage.
  12. Stalling when doing hard stops, combined with all you have said above is pointing to leaking needles and seats in the carbs, or sinking floats.
    That plug is crazy rich.
    No way out of this mate, time to pull the carbs.

    Regards, Andrew.
  13. going to the extreme there

    the reason the across runs rich is because the needle holdes in the slides are made from plastic and wear, this in turn causes the needles to raise up and the bike runs rich

    IIRC you can pull the carb tops off with the carbs left on the bike

    the plastic needle holders cost about $6 x 4
  14. thanks for the response guys, guess it's time to get my hands dirty and have a closer look at those ol' carbs of mine, yeh johnnie5 i hope you're right about them throttle slide holders i'd definately prefer just to replace those rather than mess around too much with carbies (not too mechanically knowledgeable yet) cheers fella's and goodluck to you takis hopefully one of us'll figure out how to get some more k's out of our acrosses :)
  15. Do the carb sliders it definately helped on my other halfs Across...but I would suggest doing that and getting the carbies balanced too...if you've got it apart you may as well do the lot :)
  16. Nah I would have stopped it more or less as soon as I got home. Of course, I was trying to start it for ages...

    Unfortunately although there has been a minor efficiency increase (of about 10%) that's nowhere near what I'm expecting.

    I think I'm going to go for those needles before pulling the carbs, if I read your posts right it's a bit easier to do so I may as well start with that.
  17. Ahh that's why they are wet and black. Carbs are not a simple job, but can be done at home, without any special tool (though some balance gauges really does help)

    Get a workshop manual. If you can't get one for your bike get one for any 4 cylinder inline 4, though the same brand will help. this should show you pretty clearly how to go about the carb work.
  18. All right I haven't been on for a while cause I didn't have much to report. I first swapped the air filter, cause it was filthy, and that helped a bit (maybe +10ks/tank) and tonight I've gone and replaced the throttle slide holders. I wanted to use my sister's camera to take photos but she's gone and spilt beer on it at some point so it's useless. I had to use my phone, which is kinda crappy, but better than nothing.

    This is the before shot:
    And this is the after shot:

    You can see that the holders were slipping a bit (those little white bumps in the middle), and, judging from the very small distance between richness settings on the needles, could certainly have made a difference. I hope.
    I've filled her up and restarted the counter, so will post back differences within the next couple of days. It's already idling lower than it used to (typically idled about 2.5-3.5k, now it's between 1-2k, still a bit high but definitely an improvement) but so far haven't needed to use the choke to start it.

    Also for anyone else who feels like doing this, these two sites are absolutely awesome walkthroughs:
    http://au.geocities.com/ozcross250/holder.html (doco and some photos)
    http://www.eliavecellio.com/Motorcycles/Suzuki%20GSX250F%20Across/2007-07-08%20(2)/2007-07-08%20(2).htm (no doco but a million photos)