Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Suzuki 250 Bandit running on only two cylinders

Discussion in 'Technical and Troubleshooting Torque' started by Owls71, Sep 18, 2013.

  1. morning clever bikies i'm wondering if you can help?
    my Suzuki GSF 250 bandit is not running properly (if at all) on cylinders 1&2.
    bike struggles to start and when it does the exhaust pipes of 3&4 get too hot to touch whilst pipes coming from 1&2 are just about touchable.
    I've replaced spark plugs. stripped carbs and cleaned them out with a lot of help from a mate. all put back together properly (we've checked twice!) mates convinced elec fault.
    I'm thinking poss CDI butwelcome all advice on fault finding / other ideas????
    cheers in advance

  2. Recleaned the carbs and blasted it with Carb cleaner. you could eat your dinner out of them they're that clean lol
    got the bike running on all four wahooooo!!!
    did have a small vacuum leak, would rev up ok but then wouldn't drop revs so quickly, would just slowly reduce back to tick over and even then the tick over was erratic.
    anyway eventually tracked it down to the four little O rings under each diaphragm cap. cost me $1 and bingo the bandit is now running as good as new and I'm well stoked
    • Like Like x 1
  3. Nicely done.
    • Like Like x 1
  4. Good work Owls and congrat's for having a go at diagnosing and fixing your own bike. It's a great way to help get to know your machine while saving $$$ not taking it to a shop.

    Safe riding.
    • Like Like x 1
  5. Cheers guys, whilst it was incredibly frustrating I am happy that not only did I fix the problem but I also learnt a fair bit.
    in fact last Friday morning I had an appointment to do bike training up at St Ives. wanted to get there nice and early so I got myself sorted and out to the bike only to have it not start!! because of my new found knowledge I was able to spot that the rubber boot connecting from the air box to the carb had come of on the first two carbs, as the first carb has the vacuum line that allows the fuel to flow I figured this was the problem. I took the seat and fuel tank off and re-attached the air box properly (hadn't tightened up the screws from sufficiently from previous fix) and BINGO bike fired to life.
    was still 5 mins late but they let me do the course anyway
  6. bikes not starting again :( will turn over. plugs have spark. won't fire. have had carbs off and they're super clean (I have cleaned them/taken apart a few times now). I'm wondering if too much fuel is getting through. maybe a float bowl is sticking! have taken plugs out (which are new) and each time I take them out they are wet. if not float then wondering if it's the CDI that controls firing! battery has been charged up and holds charge. I don't really know and can't really afford to be taking it in for repair!! just keep trying to eliminate things one by one, have to rely on the forums for assistance (thanks for help so far) and I'm learning a lot but it's frustrating :(
    fault has been intermittent since I got the bike 3 months ago. I clean carbs out and it's fine for week or two then same problem. this time though it's not wanting to play. when I do manage to get it started it quickly dies and cuts out then doesn't want to start again.
  7. I might have saved your money and your mechanics sanity. I am having similar problems with my Bandit.
    Look inside your carby, and there is a piece that holds the jets. Take it off and look at the O-ring like material. Is it squashed and shrunken? If so then its possible that fuel is getting past that seal causing it to run rich or even flood the cylinder hence the reason some of the cylinders may not be firing off.
    Give one of the carbys a look at to see if that is your problem. Your next task would be to somehow create a gasket for it as the part sadly doesn't exist as an oem spare (same as the O-ring material that is shaped for it)
    All the best on your endeavors.