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Need help with my Bandit 1200

Discussion in 'Tech' started by andy342, Nov 19, 2011.

  1. andy342

    andy342 Well-Known Member

    Bike is a stock 2002 Suzuki Bandit 1200.

    Starts right up, idles great. Once you get the rpms above 4-5000 or so, the bike runs as it should. It pulls hard and will run all day.

    The problem is, the bike has a bog that I cannot fix. From idle up to 4-5000 rpm, it doesn't make enough power to get out of its own way. We are talking throttle almost pinned and slipping the clutch like crazy just to get moving.

    It acts the same whether warmed up for 2 minutes, or after riding for an hour.

    I have had the carbs off 15 to 20 times over the past couple months. Tried larger pilot jets (stock 15 up to 22.5) larger mains (stock 100, up to 110 and larger) different needle positions ( 1 to 5 small washers to raise the needles )

    Unhooked the emission hoses near the fuel mixture screws, tried capping them, tried running to open air, tried leaving them hooked up. No change.

    Tried various fuel screw settings from 1 to 5 turns out

    Swapped cdi box, no change

    Swapped pickup coil, no change

    Ignition coil, no change

    New plug caps, no change

    New plugs, no change

    Messed with the throttle position sensor, no change. Back to factory setting.

    Right now the bike is back to stock jetting with the fuel screws about 3 turns out.

    Carbs are clean. Fuel flow is good. Diaphragms are not messed up. Each slide moves the same when you push it with your finger. The little o ring under the carb top is there.

    I did ditch the stock petcock for a manual one. And yes I did plug the vacuum line that went to it.

    I have not checked the valve clearances, but the bike runs so well in the upper rpms that I didn't think it was needed.

    What am I missing? Please help
     
  2. Tunersricebowl

    Tunersricebowl Fog, onward through.

    Did changing the pilot jet and opening the screws have ANY effect at all?
    If so you might check the the float level to the book specs..Suz is known to run the fuel/float level lower than normal to lean them out in the range where emissions are tested.
    Did the bike ever run right and did it ever sit up for a while?
     
  3. ACDNate

    ACDNate Well-Known Member

    Did you check the float heights?
    Fuel hose routing? Pull your manual and lay the fuel line exactly as it's shown in the book. Sounds silly but it makes a difference.
    T Vent hose position between 1/2 3/4 carbs? If I recall the T should be level to ground. Again silly but still

    Maximum-Suzuki is hands down the best resource for the B1200...
     
  4. Whit45

    Whit45 Well-Known Member

    It has to be something in the idle to mid range circut of 1 or more of the carbs. I don't see where you said you synced the carbs, but even if they were relatively close it would run better than you described. Does keeping the choke on slightly after warm-up make any difference? There has to be a restriction, varnish build up in the passages of the carb(s). A good soaking in the proper carb cleaner might help. Give Dale Walker of Holeshot a call. He is very knowledgeable of the carbed Bandits.
     
  5. afm199

    afm199 Well-Known Member

    IIRC the stocker has a restrictive airbox and needs correction. I seem to recall using a slipon, different filter and some shims under the needles plus a main jet swap being worth 10 hp. Mine carbureted well in 4th gear from 2000 rpm full rollon. No extremes , 2.25 turns, shims needles, larger mains, airbox and pipe.

    There used to be many sites that dealt with this. the 5k weak is common but yours sound too much

    http://www.portablepct.com/fastlarry/bandit_tips.htm
     
  6. afm199

    afm199 Well-Known Member

    valve adjust is nut and post really easy and quick if you want the tool I can send it to you
     
  7. ed who?

    ed who? the opposite of eharmony.

    play with float level. Also these bikes liked timing advanced for better low end. Dont mess with main jet, it has zero effect that low. get mix screws set to best a/f ratio at idle and steady cruise...then needle height to best acceleration of 5-7k rpm...above that main jet selection. Most likely where your complaining about its a matter of getting pilot jet right (17.5-20 typical) then play with float level. Again try a +5* advancer for this bike on the street, really works well. Factory Pro sells one. good luck
     
  8. turner38

    turner38 Well-Known Member

    Pull the valve covewr and make sure its in time, my money says the intake cam is retarded a tooth...
    or three.
     
  9. TLR67

    TLR67 Well-Known Member

    Try it with a fuel bottle instead of the tank and see how it runs.... You might have bad gas...
     
  10. Tunersricebowl

    Tunersricebowl Fog, onward through.

    Still would like to know if it EVER ran "right" and if this complaint can be traced back to an
    "event" like sitting up for six months or perhaps a "tune up" or a Dynojet jet kit install perhaps?
    Not trying to lead the witness your honor, but knowing the whole story makes internet tuning easier.
     
  11. andy342

    andy342 Well-Known Member

    No bad gas. Had fresh gas every day due to my 130 mile long commute.

    Synced the carbs after the first time I had them off. They were pretty well dead on. I will check them again. The idle doesn't hunt around like they are out.

    I cleaned every jet and passageway the first time, and re checked the second and third. I didn't split the rack up because getting everything back is a pain, but maybe I need to.

    Tried an advancer and jet kit since everything was off anyway. With their recommended tuning the bike idled super high and ran really hot. (ridiculously lean) I progressively changed everything back from the 'kit' to stock and the bike ran better each time. Pulling the advancer off made more low end power and gave more top speed. :confused::confused::confused: I made the second test run down the same road within a few minutes of the first.

    Bike sat for at least four years before I got it. I thought I got every bit of crystallized green crud out of everywhere, but maybe that isnt true.

    Got the bike from a friend with only about 11k miles on it, and dead stock. I cannot imagine the cam timing is off or anything has been apart. Like I said, it runs just as well as my old Bandit did, once you get above 5k or so. But again, I will pop the valve cover off and check clearances and cam timing. I have set valves on these engines before and it is pretty darn easy.

    For what it's worth the bike seemed to make the most top end with 107.5 mains in it. Doesn't matter if it can't get moving though.

    Off to split the rack up I guess. Time to start poking copper strands through everywhere. Thanks for the ideas, and I'll let you know what I find in the next couple days.
     
  12. Tunersricebowl

    Tunersricebowl Fog, onward through.

    Splitting the rack is a big waste of time and there is nothing to be gained from doing so.
    Tear the carbs down (one last time) and soak them in Yama carb cleaner OR shit can the whole mess and get a good used set and be done.
     
  13. Tunersricebowl

    Tunersricebowl Fog, onward through.

    I forgot to ask which jet kit was installed?
    Did the slide air bleed holes get drilled or modified?
     
  14. afm199

    afm199 Well-Known Member

    Again, the original had a bad lean spot at 5k. Read the website. The bandit 12 REALLY benefits from airbox mod, slip on and minor carb changes. The intake snorkel is tiny.
     
  15. Tunersricebowl

    Tunersricebowl Fog, onward through.

    Hey thanks for the advice on what to read there guy!
    BUT my interpretation is that a small airbox inlet will INCREASE low rpm torque, not reduce it.
    The bike sat up and the fuel turned to varnish/sludge.
    That is his problem, well really it's not using proper cleaning procedures and chemicals.
    AFTER the varnish problem is cured if he wants it to run better than stock he can do all sorts of mods and I can recommend some myself but he is not asking how to make it run better than stock, but rather how to make it run at all below a given threshold.
     
  16. ed who?

    ed who? the opposite of eharmony.

    pull the snorkel! PERIOD!! Again main jets have NOTHING to do with low rpm! I have also never seen a stock GSF1200 not benefit from advancing the ignition timing.
    Good luck thou.
     
  17. Vitamin-E

    Vitamin-E cornerin lo in the 3-1-fo

    So its not an R6 but...my R6 did the same thing for awhile last year. It WAS a TPS situation. It wasn't out of adjustment but it needed cleaning. I took it off the bike and sprayed it out with ELECTRONIC PARTS CLEANER (not contact cleaner) that can be had at Advance Auto. Put it back on the bike, adjusted it and fixed.
     
  18. loser

    loser Well-Known Member

    Well there you have it. It's a dirty Throttle Position Sensor...:)
     
  19. madriders86

    madriders86 Well-Known Member

    Some of these responses are hilarious.

    I'm willing to bet money the problem is some dirty passages...or something else with the carbs.
     
  20. turner38

    turner38 Well-Known Member

    So pretell, what clogged passages will cause a lean spot from idle to 5k At part throttle but still allow it to idle well and run well above 5k?

    ANYTIME you have a issue such as this you should first verify the mechanical side of things, compression, valve clearance and cam timing.

    I have seen a missing snorkel cause similar issue's on other bikes but never ran across that on this model plus it seems as though he's chased the jetting around enough he would have tuned it out if this was the case...
     

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