1999 CB400SF Engine cuts

[CalRamCB400SF]

Hi everyone, I'm new to 400GreyBike so 1st of all hi!

I bought a 2nd hand Honda CB400SF (1999) about 3 months ago and I'm having a lil trouble with it... When I twist the throttle,lets say all the way to accelerate quickly,the engine begins to cut and 'mutter'... I have to do this slowly inorder to reach all the revs desired.. Its almost like something is "choking" something like blocking some sort of pipe,hole, or whatever.

Ive had my carb cleaned so dont think thats the problem and had my spark plugs replaced recently 2 brand new iridiums (CR9EHIX-9 which is meant for the bike). Aftr a ride, i decided 2 check the condition of the S.Plugs n there was carbon all over em(brand new S.Plugs!!) Which means the air-fuel ratio is 2 rich. Could this be happening if its not getting a constant airflow? Could the ignition coils cause tht also??

Please help!! Thanks in advance

[Superjack44]

Could be the fuel flow is being restricted, turn the fuel tap to off ( pointing towards the rear) remove the small bowl under the tap and check for cleanliness, next job if it's clean check for fuel flow by removing the vacumm pipe from the petrol tap then the fuel pipe from the rear of the tap turning the tap back to the on position and then connect a small pipe to the vacumm side of the tap suck on it and you should see a good flow not a dribble but a good flow if it's only dribbling you will have to drain the tank and remove the complete tap and clean the internal filter , it's a simple job.
You could also see if the petrol tank breather is ok if its blocked you could get similar symptoms , to remove the tank remove the two 10mm bolts at the rear of the tank and there are two rubber pipes the larger is for draining water from the well of the petrol tank filler the smaller is to allow the tank to breath while the engine is running try lifting the small pipe and sucking to see if the pipe is clear (dont breath in) if it's not ( I had this problem) I inserted a broken piece of bowden cable and pushed it up the smallest of the two pipes while twisting it at the same time and managed to clear a blockage my bike has been running fine ever since.

[amorti]

Hi and welcome!

Do us a favour and leave the txt spk at the door, please?

Have you checked the condition of the air filter yet?