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My son recently purchased an 82 Nighthawk 650. The bike is in great shape, and the previous owner had the carbs completely re-built, and the fuel shut off valve replaced. The bike runs great, but sometimes it when it is hot, during stop and go traffic, it will just quit. It is getting gas, and if he lets it cool for a bit it fires up fine with no problems. Any suggestions on where to start checking? Battery is new, and there is always plenty of juice to crank.
 

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Next time it shuts off try to remove the gas cap and see if it starts up after a few seconds. There could be a venting issue.
 

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Old Hondas

I have 8 of them . Your problem occurs when the bike is hot, so it is a conditional problem. If you can rule out fuel or electrical, you are half way there.
I highly recommend that you get a timing light. A cheap one like this is fine
http://www.harborfreight.com/xenon-timing-light-3343.html then, when the problem happens, you will know right away if the spark is happening. Considering the age of your bike, even electronic spark systems can start breaking down when heat is present. I like timing lights because they will show even occasional misses and the shadetree tests for spark often do not.
For 20 bucks,it is a no brainer for me. Use a 20% off coupon and it becomes sixteen...

I have a Honda Magna [1983] that had a problem similar to yours and even when it was running pretty well, the timing light showed that things were not quite right. It took a lot of persistence as the coils, spark boxes, and pulse generator all could be the cause of two dead cylinders that died and then came back to life.
Do not overlook the square plastic connections in the wiring harness. Signs of melting or corrosionor just getting loose will ofter cause the connection to break down when the bike gets hot. Bullets connectors get loose as well and Honda bikes often lose power when they heat up. These guys have them and you do not have to wait long to get them. http://www.cycleterminal.com/250-connectors.html

Do not rule out valves and such things either. It is always best to get your bike up to scheduled maintenance standards to help rule out as many things as possible
 
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