carb problem

i have a 77 kz 650 and the thing runs great at startup and for about 4 minutes then it seems to loose fuel and there is no throttle response. it will eventually die. there are two thoughts : the choke is somehow stuck on inside or it is truly running out of fuel some how. when it has idled for a few minutes and you give it the gas it will die so i've taken the carbs off for the third time but mabye some of you will know what i should look for. thanks d.j. p.s i'm in denver and looking for a club and or member/mechanic to tweak this stock bike to make it perform at its best.

try putting a piece of clear battery vent tube on the drain nipple on the bottom of the carb, make a shallow loop and run the end up higher than the carbs. Then open the drain screw, the same scenario as a fuel level check. then start the bike and watch the fuel level see if and how muck it drops. if that is fine check the petcock and the screen that is attached yo it in the tank. the screen is really fine and plugs fairly easilly

the other thing i didnt mention is that it will start up right away and then fade but when it cools down it will repeat the whole process until it's warm again...??? anyway that is a great suggestion, i'll try that. thanks d.j.

Fuel tank cap vent may be clogged. Might try running with cap loose (not snapped down) and see if the same symptoms appear.

Could be a clogged in-line fuel filter, or a kinked fuel line, or a dirty petcock bowl screen.

Crud inside the tank can clog petcock tubes. Remedy by removing tank and flushing with fresh gasoline. And removing, disassembling and cleaning the petcock.

cudadeej7 wrote:

the other thing i didnt mention is that it will start up right away and then fade but when it cools down it will repeat the whole process until it's warm again...??? anyway that is a great suggestion, i'll try that. thanks d.j.

Typical symptom of fuel starvation from some type of restriction. "Cool down" is coincidental, because engine is off. The key, most likely is that when your engine is off, the fuel can drip slowly and refill the bowl and lines so it will run off of this new supply when engine is restarted.
All the posted tips by patton (see above) are issues to check before going into carbs to look for the problem.

Post edited by: JimatMilkyWay, at: 2007/02/23 09:46

thanks for the help. i'll let you know as soon as this snow stops and i can go outside again .....:whistle:

thanks for the help. i'll let you know as soon as this snow stops and i can go outside again .....:whistle:

thanks for the help. i'll let you know as soon as this snow stops and i can go outside again .....:whistle:

cudadeej7 wrote:

thanks for the help. i'll let you know as soon as this snow stops and i can go outside again .....:whistle:

Your welcome, your welcome, your welcome.
And welcome to the forum too.

cudadeej7 wrote:

the other thing i didnt mention is that it will start up right away and then fade but when it cools down it will repeat the whole process until it's warm again...??? anyway that is a great suggestion, i'll try that. thanks d.j.

my old honda cb750 would do this. the coils would warm up and one of them would quit working. let it cool down and it would work. just a thought..