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.

Bandit 1200 'coughing' with a full tank

Discussion in 'Technical and Troubleshooting Torque' started by Bravus, Jun 10, 2014.

  1. Bit of a weird one. My Bandit would stop firing for a second or two, then go again (and often backfire on the unburned fuel) on a particular section of the M1 north from the Gold Coast to Brisbane. Disconcerting on a freeway full of tailgating c0cks.

    I wondered whether it was the throttle just slipping in my hand, or me losing attention. I wondered whether the reg/rec might be on it's way out.

    Set out to ride to Toowoomba yesterday, and it nearly got bad enough to make me turn back. Scared of getting stranded.

    But then it went away. And, thinking it through, I realised it's not alien emanations in that sector of the M1. It's that I usually fill up with fuel before making the trip to Brisbane! The issue is associated with a full tank.

    Guess I can just keep the tank a little less full - and the internets have some info about cleaning fuel tank vent hoses.

    Any other suggestions, though, in relation to what is still a pretty tentative diagnosis, would be very welcome.
  2. check fuel delivery systems or maybe carb settings?
  3. could be a partially blocked tank vent.
  4. If it was fuel delivery there would there be any unburnt fuel to backfire ?

    I'd be looking at the condition of the plugs.
  5. Will check plugs, but it'd seem odd if that correlated with tank fullness. Plus it seems like all 4 stop at the same time.

    Couple of YouTube vids on cleaning vents that I'll watch tonight.
  6. (Could be correlated with engine heat rather than tank fullness, I guess)
  7. Moisture/crap in the fuel itself, just passing through the system/carb.

    I have had similiar experience, and believe it to be a little bit of water in the fuel; coughed and spluttered for 20 minutes, then perfect for the rest of the day (although, that was on a FI bike).
  8. I'm fuelling at a United. Might get the tank pretty empty and get my fuel elsewhere, see if there's a difference.
  9. Good point about all four going out at once. If you're picking up moisture that could kill all four plugs at once but it seems a bit unlikely.

    CDI getting sensitive as it passes through a particular heat range?
  10. I had a similar thing happen to my Bandit a few months ago. Bad fuel was the culprit. I emptied the tank (by riding it 250km) then a added 'carby cleaner' before filling it bac up.

    As a side note, it seems to have helped with my winter carby icing problem as well.
  11. Hi Bravus,

    I had the odd issue with my 1200 Bandit. Dirty petrol could be the culprit. Suggest 1/2 cup of metho which will take any water through the system without damage to the motor.

    I would certainly check the vent in the tank as that is what it sounds like.

    Plugs, I had an issue with stale juice which coats the electrodes of the plugs which prevents them from firing. Had me beat for a few weeks. Motor would turn over but wouldn't fire. Ended up buying 4 plugs, threw them in and it fired into action in a micro second.

    It could be one of the 3 issues above, or a 4th that I don't know about.

    Best of luck.
  12. Bugger: kept everything else the same but changed the fuel supplier, and still got the same result. Definitely associated with the full tank (but I'll try filling the tank then waiting a while and seeing if it's that or temperature) because it happened at the same place as always, and then stopped. I'll try the metho trick in case there's still some water in the tank. The particular bit of road has bumps, which could be shaking it up. Seems unlikely to be the tank vent because that would be stopping the fuel coming through, so the unburned fuel backfire wouldn't happen.

    It's overdue for a major service, so I might end up just leaving it for the mechanic to sort.
  13. The symptoms really sound like electrical to me, though I'm buggered if I know how the full tank can cause an ignition problem. You might be right about the correlation with heat. I'd be checking for loose or bad connections. Start with the battery terminals, make sure they are clean & tight. Perhaps replace ignition fuse with another one to eliminate a dodgy fuse. Then make sure ignition switch & kill switches are not worn by giving them a wriggle with the engine running and see if you can induce a misfire. Also turn the handlebars lock to lock with engine running, and wriggle wire harness around steering stem, as wires in this area can be stressed & broken by handlebar movement.
    Apart from these common causes for cut out, there are some less common / more difficult to determine causes, such as faulty pickup coil, side stand cut out switch, CDI unit, etc....
  14. Ooohhh - side stand does spark off a thought - bumpy bit of road...

    Will try the other stuff you suggest too - I think I agree, the full set of symptoms does seem more electrical.