I just picked up a CBR, its a 94 frame, the plastic, engine, wheels are 95 and the rear swing arm is off a 97, its a nice looking bike, had some issues with the fuel pump, wasn't shutting off, so i gravity feed the pig, which i leaned i could do on this forum. it was running off of 3 cylinders until i rode it for a while, now its miss firing at high speeds, well more like 80 or 90. the plugs are new we just changed them and still does it, any ideas here guys?

 

You getting enought fuel to all cylinders? or are your bowls emptying themselves when you are looking for more fuel than your gravity feed can give them?

 

NO, GETTNG THE FUEL, THE LINES ARE 3/8'S AND THE NEEDLE FLOATS AND SEATS ARE OUT OF A 96, WHICH IS GRAVITY FEED, WE CHECKED THT ONE RIGHT OFF THE BAT.

 

coils?

 

thats what i was thinking, we have tested them today and they seem fine,

 

ok, this will sound stupid, but: is the battery in good condition,(your not jumping it off to ride are you ??)holding proper charge, etc ?? had this happen before, bike starts, idles good, when ridden fast or idled up fast at a stand still, the motor stutters and cuts out. also. sounds like it could also be a carb issue. The pilot circuit jets and passagewayscould be obstructed, trying tearingdown the carbs and see if you can see light through the ports, passages, etc.not sure of that year, but if the carb had/has floats, theycould be sticking at high speeds stopping your gas flow or giving you too much. or if you prefer, go to a parts store and buy "sea foam", add to the gas tank and try it a day or so, works wonders sometimes, especially if there is a chance of moisture in the fuel...

 

so figured it out, there was a vacume port on cylinder 4's manifold that wasn't pluged. we put a plug on it and try'd it out, it rode like a dream, i thank all who gave me some input on my issue, it was a big help.

 

And everyone lived happily ever after.....