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need some desperate help VFR400 track bike

Discussion in 'Technical and Troubleshooting Torque' started by davvis, Jun 4, 2009.

  1. Hi all.
    I am in desperate need of some help here. My vfr400 track bike is playing up and i have a track day monday.. I know its cutting it very fine but i only just found out it has a problem, and the mechanic would have no chance to squeeze me in, so its up to me

    the bike starts and idols fine. jump on it and try to test it out, it SEEMS to rev right up to about 3k or 4k rpm then just starts running very rough. wont rev and feels like its missing/running on 2 cylinders or something

    a bit of back ground on the bike
    i have used it on one track day before, and before this day it was also running like a little biatch, rough through all revs. sent the bike to the mechanic and they cleaned a whole heap of gunk out of the carbs. bike was running sweet. So after that day i thought, in my great wisdom, i would cut the wiring loom down to get rid of all the lights etc. Plugged it all back in and tried to start it--nothing, figuring i cut something important i replaced the loom with a new one and it then started. Today putting the fairings back on i started it, idoled fine. Tried to test run it and rough above 3k rpm

    the bike has a full tank of new and clean fuel. battery was putting out 14v bike has new plugs also

    any suggestions? i dont know to many mechanical terms for the parts but if i have all the solutions simplified i should be able to sort it out

    its a race against time because i know if i take my road bike to the track i will end up sliding it somehow...

    so please help me with any suggestions

  2. probably need to go back over the carbies, lower the needle setting/smaller main jet, if it's riching out. Could be a number of things though. Best bet is to take it up the freeway and sus it out.
  3. I had a problem like this. Was a lemon of the highest order. Absolute money pit.

    Awesome bikes when they work well, pigs when they don't.
  4. It could be linked to the electronic ignition.
  5. after careful examination of the symptoms i think ive worked out whats wrong with it...

    its a honda :p
  6. es, you are a bad girl.
  7. Does it actually rev over 3k rpm at all? or does it cut out so that it wont run above that? My brother has a cbr25orr and ended up shorting out the circuit that controls the lights, the bike ran fine to 5k rpm but would not go over, the ignition would cut out and basically just prevent it from revving above this mark. As soon as we replaced the fuse the bike ran great again.

    Your problem sounds very similar to this... except that you've cut the lights out. Try checking your fuses, if they are fine then you can try doing something with the wiring loom like inserting a resistor, but thats up to you.
  8. Coming from you Rog, she'll take that as high praise indeed. :LOL:
  9. Check (and double check :p ) that all your hoses and pipes are not kinked or bent at sharp angles, and plugged in where they should be. Refer to your workshop manul for how many hoses there should be, and where they should go. Pay particular attention to fuel and air hoses, or hoses to air solenoids (if fitted).