84 gs400 limited run time

[atrent]

I have an 1984 GS400 that I saved from the junk yard. It was rather a sad looking case. Installed new o rings, washers and springs on idle air screws (they were missing). Did a fast clean up of the carbs and the bike has been cleaned up and was running reasonable well. Very easy starting etc. Started to run a bit rough so took off the carbs and cleaned them in carb cleaner. replaced the boot o rings, new plugs, reinstalled carbs and now it will only run for a few seconds maybe a minute and it slowly dies. Will not start again. Leave it for a few minutes, 2 or 3, and it will start and run for a short time again. Good fuel flow to the carbs so the fuel supply doesn't seem to be a problem. Spark is not the greatest but there is spark. My daughters GS250 has a fatter spark. Coil primary ohms approx 4, secondary 22k on one and 21k on the other. 12.5 volts at coil primary and the igniter pulses can be observed with the multimeter. Considered swapping igniters with the 250 but they are not the same. The tank is off and a temp fuel tank consisting on a one gallon can is being used so no petcock to cause concern. I have about come to the end of my ideas and am looking for some more experienced help.
alex
I posted this first as an electrical problem but since I can't seem to find any significant electric issues I wonder if it can be fuel related. Throttle stop set to idle at 4.5k R.P.M., starts and drops quickly to 4k holds for a very short period then slowly drops and around 1.5k it just stops. Won't start again until it has sat for maybe 2 minutes then the same procedure.
alex

[tom203]

Trying to confuse us mentally challenged folks by switching categories?
Anyways, I assume two cylinder, two coils, setup something like a 450?
Can you get a part number off ignitor box?
Have you tried manually grounding the coil(s) to see if spark looks better with ignitor out of the picture? It seems like you got fuel system covered, so I'm getting fixated on ignition.

[atrent]

Trying to confuse us mentally challenged folks by switching categories?
Anyways, I assume two cylinder, two coils, setup something like a 450?
Can you get a part number off ignitor box?
Have you tried manually grounding the coil(s) to see if spark looks better with ignitor out of the picture? It seems like you got fuel system covered, so I'm getting fixated on ignition.

correct 2 coils etc. What do you mean by "grounding the coil"?
alex

[tom203]

remember- I'm not familiar with this model, but I don't see why the basics aren't the same.
With ignition on, the coil gets 12 volt to plus side ( orange/white wire ?); when signal generator pulses to ignitor , the ignitor grounds the negative side of coil suddenly, which causes the plug to fire. If you remove this wire from coil, you can use a jumper wire from this negative spot on coil to a good known ground - just momentarily touch it. If your spark seems better, let me know.