2006 Rincon 680 starts run for about 1 hr then sputters and acts like it is running out of fuel. At that point it can be shut down for 15 min then starts and runs normal again for about 1 hr

 

Does it do it under load? do you ride it for 1 hr or just let it sit and run?
It looks to me that it does get probably hot!
Is it EFI or just regular carb?
I have a 03 650 Rincon that I completely rebuilt (new crankshaft, new flywheel, new stator, new rings....)
I would suggest to start with removing the carb cleaning it throughly, then next will be to check the valves adjustment and let me know what results you get. Thanks.

 

if it's running fine for an hour and then dies- it can't be anything with the motor.

a mechanical issue like valves, piston, rings or bearings etc.... will show up as soon as the motor starts and warms up. The motor will be at full operating temp with in 5-15 minutes- unless you have a stuck stat in the cooling system.

sounds like a fuel issue- plugged vent line, vapor lock, bad fuel sloshing around, maybe a defective efi sensor...

The fact that it's running for an hour before it starts to die rules out most common mechanical failures.

 

X2 on what BeerGut said, my initial thought is blocked fuel vent line or faulty gas cap.

 

We dropped the fuel pump out cleaned the crud out and replaced fuel sock. I was told it was running better.