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Suzuki Bandit GSF250 Intermittent won't start.

Discussion in 'Technical and Troubleshooting Torque' started by LB, Sep 4, 2008.

  1. MOD: next time don't post topic heading in all CAPS.

    Hi guys,

    New to this site, I found this site is very informative in regards to technical issue of the motorbike.

    I'm having problem with my bandit gsf250 1995 gray import.
    Intermittently wont start. most of the time in cold morning if I'm going to use
    the bike to work.
    the symptoms is, If it fail to start the bike in fist go, "IT WILL NOT START AT ALL" I need to wait for at least 30 min to start again. And if you are lucky it will start. This happen a few time now and I'm loosing confidence on my bike.

    Things that I've done on my bike are:
    >new oil
    >new filter
    >new spark plug

    But the problem still there. So I decided to bring it to the mechanics. The mechanics work in suzuki service center. after 3 weeks the mechanics can't give me an answer of what might be causing of the problem. He told me that he strip the carby and give a good clean, balance and adjust the jets. I'm running out of Patient to the mechanics and also to the bike.

    My Question is:
    Is anyone can give some technical help?
    any mechanics that you can recommend to solve the problem of my bike?
    I'm located in North West Sydney.

    All your input is highly appreciated
  2. It is difficult to diagnose over the internet, however I will give it a go.
    From your information:
    1. Won't start when left for long periods, particularly cold mornings.
    2. It's a gray import
    3. The problem is intermittant
    4. The carbs has been cleaned, adjusted and balanced
    5. New plugs, air filter and oil.
    It's a bit like a jigsaw puzzle with lots of missing pieces.

    I always go back to basics.
    The engine needs air and petrol at a ratio of between 12 and 16-1. The richer mixture (12-1) is for starting and the leaner (16-1) for normal running.
    It needs to compress this mixture sufficiently to to about 1,000 Kpa (150 psi). Providing the bore, piston, rings and valves are in good condition this is unlikely to be an issue.
    It needs a sufficiently strong spark at the correct time to ignite this mixture.
    To check for fuel starvation, buy a can of starter fluid. Squirt a little in the inlet. You may have to remove the air filter. If it fires up, or keeps running for short period then fuel starvation is the problem.
    Fuel starvation? Is fuel getting to the float bowls? Unscrew a drain plug from one of the bowls. Does fuel run out? Yes? Go to ignition system. Intermittent spark loss? Check battery terminal and connections to ignition module. Check that high tension leads are plugged fully.
    Take a plug lead off and track to cylinder head to check presence of spark when cranking engine over with starter.
    Gray imports usually come in containers on ships. They may spend weeks in a damp and salty environment. Water can condense in tanks. Rust flakes may form and block fuel taps or mesh filters. Check flow of fuel from fuel tap. Sometimes rust flakes or dirt can float around the bottom of a tank so overnight it may settle at the bottom of the tank. Blockage could depend on if bike left on side or centre stand. If this bike has a electric mixture enriching solenoid then the electrical connection may be loose or intermittent. This may make for difficult starting. Ignition switch? Kill switch? Shorting spark. Rusty contacts?

    I could go on and on and I usually do! I hope these may be some helpful suggestions. There could be a zillion others but the basic principles of fuel, spark and compression remain. If you are in Northwest Sydney then the folks Motor Cycle Accessory Warehouse on Victoria Avenue Castle Hill have been very helpful to me. They have a mechanical service.

    Bob Moore
  3. Hi Bob,

    Thank you for your very informative reply.
    When the fault of my bike showed up, I checked the following part of the bike as a preliminary diagnostic.

    1. removed the fuel tap and cleaned. (The mesh is not that dirty but i blow it with air compressor.
    2. I checked the spark one by one if it present while I press the start button. The spark is there all four spark plug have spark.
    3. I unscrew the fuel the drain plug and there is a fuel there.
    4. I always make sure the battery is fully charge by charge before i attempt to start the engine.

    If the engine start, it will straggle a bit until it pick up the revs. most of the time i need to hold the accelerator for about a min. to keep it going but once ti settle it idle smooth on 1800 rpm. I notice the bike don't want me to use the chock. if i use it struggle the rev. and the engine will die and i wont be able to start again for another 30 min. minimum.
    My mechanic told me that he check the compression and its all ok.
    and also he told me that he re-jet the carby. not sure if its true!!!!!
    I believe the problem is in carby. correct me if i'm wrong.

    Do i need to replace the carby?
    Does it need a carby kit? if there's any?
    would this be a big problem?

    MAC mechanic is on my list and also the Castle hill motorcycle.

    Anyway i will try your suggestion by spraying Start ya bastard and see how it go. Thank you for your help. cheers LB
  4. Dow are the plugs if it doesn't start? are the plugs fouling? the engine doesn't "know" it cranked ten minutes ago; conditions in the combustion chamber are causing it to not want to crank. In my mind there are three possibilities
    The battery is ratshit.
    Your carbs are incorrectly adjusted and fouling the plugs, as the fuel evaporates, you are able to crank again.
    Your choke system is blocked (unlikely on a 4 cylinder)
  5. Hi there,

    Just an update to my bandit. I started the bike in a normal way this afternoon around 3pm with 20F deg. temperature and the bike start 1st go without using the chock.
    I run it for about 15 min. rev it in and out and the idle steady in 1800rpm without any fluctuation on my Tacho.

    I will try again in the morning if it will start again and see how it goes. It’s hard to diagnose this bike especially if the fault is intermittent.

    If the cardy is running reach would it make the same symptoms?
    If the plug fouls would it start again once it’s dried up?

    Cheers guys,
  6. This sounds like your choke is not working. Check that it is.
    What is your normal start procedure?
    An engine that is running correctly will start (cold) on full choke without any throttle.
    Once it catches you can back the throttle off until it warms up (it will warm quicker if its used)
    I think your choke is not working and after cranking for a period you are flooding the engine.
    Was the mechanic able to get it started?
  7. Hi Cris

    Before I send to the mechanics I normally start the bike in cold morning with full chock. And the bike start.
    I send the bike to the mechanic to get it fix, and when I received the bike it won’t start with full chock, once the bike warms up and try to use the chock just to check if its working, the bike struggle to hold the revs and the engine die. Now I can’t use the chock. Something is not correct on my carby.

    The mechanic manages to start the engine but he told me that the engine is running reach.
    And he strips the carby few times but the problem still there. He put a new hotter plug. Not sure if it solve the problem. Not really sure where to go.
    I will try few days or weeks to start the bike and see how it goes. I’m just worried to use the bike that might die on me in the middle of nowhere.

    Thank you for your input Cris.

  8. I don't agree with the mechanic changing the heat range of the plug. This is just covering up one problem and creating another potential problem.
    It is important to get to the cause of the problem, not just masking the symptoms of over richness. If the plug is fouling due to rich fuel mixture, the cause of the richness needs to be found. If the plug may work OK for a while but it could be liable to overheating and cause detonation (pinging) which may result in piston damage.
    I am not familiar with your Suzuki model. Some manufacurers have adopted more automotive style temperature sensors and solenoid controled mixture enriching in conjunction with manual choke. There may also be a connection between temperature sensor and ignition module that controls spark advance. It seems you have eliminated all the likely problems such as fuel tap blockage, fuel in float bowl, correctly adjusted float height, mixture screws, idle speed adjustment, spark quality , ignition timing. In the last 10 years, more and more bikes have needed to comply with stringent emission laws. I don't know what devices that have been included (such as crankcase ventilation valve) may cause your problems. The main clue is that when the motor warms it is running OK but it needs excessive time to run smoothly. Either it is running lean when cold and as it warms the fuel is better atomised or it is running too rich when cold and as it warms up a temperature sensor eventually gets to turn the mixture enrichment off or the temperature sensor (if it exists) is not working properly and the mixture enrichment circuit is turning off too late because it "thinks" the motor is still cold. It sounds like your motor is running too rich from a choke that is not turning off correctly. I don't how your "choke" works but if it is a flap valve in your carburettors, it could be sticking in the on position even after you have turned it off. It may turn off after the engine is running and vibrating for a while. Solenoid choke? see above. If temperature sensor, change that or check resistance to see within specs.
    Other things to cause uneven, rough running with difficult starting, intake air leaks, valve adjustment.

  9. I sugest taking it to another mechanic ...What sort of KM has it done it could be valves ..It sounds rich as so the most likely cause is carby ..
  10. Hi there,
    Just an update to my bike, I take it out for a quick ride and now the bike run like a dog. "Flat spot on the low revs. and hesitate to rev. when i get home, i removed the spark plug and its dead black. The bike is running too reach.
    To be Honest the bike runs well when it start before i send to the mechanics, but now runs like dog. Very upset to the mechanics.
    I choose a wrong mechanic.

    My question is:
    What is the setting for:
    1. Pilot Jet
    2. Main Jet
    3. pilot Screw (preset by 1.5 turns out)

    Now the bike's running crap i might as well try to clean my self and adjust the jets. i have the service manual with me but no information to the pilot and main jets setting.

    Regards LB
  11. I sugest taking it to another mechanic ...What sort of KM has it done it could be valves ..It sounds rich as so the most likely cause is carby ..

    Hi Traviss,

    My bike only done 30330Klm. The mechanic checked the compression test and its ok.
    Yes I'm going bring it to another mechanic.

    If the bike is a grey import, for instance my gsf250, does it make a differece to a gsf250 bike that sold here by a dealer channel?

    Is the princible of the Carby of the grey import different to the llocal market bike?

    Regards LB
  12. Its not a beginners sort of thing you need vacum gauges to get it right and balance ,How many carby's does it have ..
    As for the compresion test I wouldnt trust anything that mechanic done he may not of done it and just stuffed up your carby's .The mixture is most likly out your balance might be out you float level out it might even be Electrical ..Take it to a good mechanic and start again explain what happened without bagging the other bloke to much someone will have parts for it if you cant get origanal ...