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Engine cut out

Discussion in 'Technical and Troubleshooting Torque' started by Project, Jun 6, 2010.

  1. Hi, well I was riding home today on the CBR125R, think I was doing 8000 rpm in 4th when suddenly the bike started jerking, the engine cut out and the FI light came on.
    I clutched in and kept her cruising and pulled into a side street. Tried restarting with clutch in on the ignition but no sound at all.
    Dropped it back down to neutral, checked the front light and N indicator still worked, so I'm not sure if its a battery problem.
    So I turned the FI cutoff off then on, then hit the ignition again and she started up just fine.
    It happened a few times again before I got home, each time sort of jerking and the FI light coming on. I clutch in to stop the jerks and keep her freewheeling (in moving traffic >.<) cycling the cutoff switch and starting her up again. Happened total maybe 6 or 7 times.

    - I thought it may have been a certain gear, but the cutouts kept happening as far as I remember in every gear from 2nd to 5th at various times

    - It seems to happen usually under throttle load, when it hits higher rev ranges. The bike redlines at 11000 rpm, and I notice the cuts occur usually around 8000+ rpm after heavy acceleration

    - It might be related, but I feather the clutch a bit after a gear change to find the friction point (not sure if this is the right technique!), and I found that it stopped happening if I let the clutch out fully and immediately on a shift, at the risk of making the bike jerk a little

    - I seemed to be able to prevent it in the last few kms home, if I kept the revs low and the gear changes really quick, and be excruciatingly easy on the throttle (though others who have ridden 125s understand you need to be quite trigger happy to get the little things to go anywhere!)

    Anyone got any ideas?
  2. I'd ask if there was a fuel leak somewhere in the system but I'd imagine you'd notice that quite easily when its pumping out around 3 bar of pressure...

    Perhaps the pump is dying for some reason, or a filter is clogged causing the pump to work harder than it should.. especially at high rpm.

    I'm more of a carby kinda guy so I can't think of anything else off the top of my head, apart from getting a diagnostics device to plug into the ecu and see what the error code is.
  3. Sorry to make a stupid assumption here, but that actually sounds like you don't have enough fuel/air reaching engine.

    Firstly, is your tank empty?

    If not, when you leave the bike parked, can you see any petrol dripping underneath the bike?
  4. Side stand switch.
  5. Is it still under warranty? If so, let the dealer have the headache.