a friend of mine has a 2003 sportsman 700 non-efi that runs rough and stalls when hot. this usually only takes a few minutes. we thought running hot was the issue. the water pump is working and water is making its way through the engine. checked thermostat and it opened in boiling water closed when cooled. don't know the temp of the water though. while removing the radiator cap there was never any pressure under the cap even when machine was hot. it was not losing water anywhere. he bought another cap at an auto parts store that had a 13 on it. is this too much? the older cap has 0.9 on it. the engine never feels extremely hot but it only acts up when warm or hot. overheat light hasn't come on. is see this same problem on here a lot with several different solutions from carb cleaner to vapor lock. just trying to find good info on troubleshooting this particular issue. he did mention that he never had this problem before when using non-ethanol gas.