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 bitch, 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

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

this is going to be your speedo cutout - check the speedo is connected and if you have a de-restrictor then ensure it is connected

Oh yes..amd welcome too...

Have you removed the speedo?

thanks, sorry i didnt introduce myself. i am kind of a bit flustered at the moment

speedo was disconnected before i bought the bike.
I have read something about the bike running like shit when you remove the speedo, what can be done to a standard loom if you have no speedo?

Rick o does a little plug for £6 which basically just connects 2 wires with a resistor

Get a 2.5k resistor and solder it between the orange/blue and green wires (clock end of the loom) like in this wiring diagram. It should solve the problem.

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do you think this would definately be the problem?
i can rev the bike seemingly ok at idol and under no load, but once i am on it will only go to 3 grand or so and then run shit? sound like the speedo cut out?

ok Clock end of the loom?? what does that mean

is it right that if a find the orange/blue and green wire at the front of the loom (where the speedo used to be and where the tacho and temp gauges are) and solder a 2.5k ohm resister in it should fix my F**k up?

yes - this will be the problem. The CDI has gone into limp home mode as it cannot detect the speedo is attached.

You solder the resistor onto the wires as Martin says and this tricks it into seeing a speedo.

It is a common fault

You'll find the cutout is at 5.5k revs. sounds horrible.

Where you based? Might be able to give a hand if close by??

i am unsure if it messed out at 5.5k, but it did seam to run fine to a certain rev amount then it f'd out.
i just had a look and it shoule be pretty easy to bodge up, ill just buy a resistor tomorrow.
so its the orange/blue to any of the green wires? as they all join into each other?

also i live in australia,
so thanks but it might be a bit of a commute for you :)