Motorcycle Repair: 85 CR500 wont stay running, fuel contamination, cr500

Question
When I start my bike it will run great for a few minutes then die suddenly like I forgot to turn on the gas.  I put a new fuel valve on the gas tank and a new float valve in the carb checked the float level and checked the fuel flow by opening the drain plug on the bottom of the carb and turning on the gas...all looks good...
What else could cause this problem?    Thanks  

Answer
Hi Scott,

If fuel delivery is constant, check charging system and ignition systems for proper operation.

There may be an intermittant fuel obstruction caused by fuel contamination, pinched or collapsed hose.

There may be an electrical problem that occurs now and then caused by a frayed or loose conductor or connector, corrosion, or water shorting.

I suspect the problem is simple in nature. I suspect the diagnosis will be difficult.

Respectfully,
Mark Shively