83' XR500 rebuild. Bike runs, won't throttle up.

A friend of mine has so far done a good job of rebuilding the motor on my old 83'. The bike starts and runs great but kills when throttle is applied.

He says it feels like it is starving for fuel and is not flooding. He went through the carbs completely and still has the same problem. The bike ran OK before rebuild.

Could this be a timing or valve issue ? Timing chain too old/stretched maybe ?

Looking for suggestions. Thanks for the help.

I would suspect the carb. Check for incorrect assembly.

I put my 600 together once with the cam chain off by one tooth. The engine ran, but not very well. It didn't just die when the throttle was applied.

I had this type of issue with water in the gas. A drop of water go in the main jet and this basically clogged it. It would start great, but as soon as I gassed it, the engine died. Took me a while to figure it out.

the 83 is real picky on float level. Don't go by the specs on a 84 (same dual carbs different settings) if it's too rich it won't start if it's too lean it won't run . Open up the bowl drain screws to see just how much fuel is flowing,let it flow for about 10 seconds .Also look under the needle and seat when you have the bowl off .

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