'99 CBR F4 stalls when hot

Sounds like its running overly rich (like getting too much fuel) when warm. The first thing I would do is pull the air filter and see how cruddy it is. If it checks out ok or is fairly new then my next order of business is give it some new plugs. When you pull them out if they are all black on the tips you are deffinatly getting too much fuel. Then its time for either carb adjustments or a good carb cleaning.

Don't rule out an ignition problem. When things get hot, parts like the coils and CDI sometimes fail but will work when cool.

hmm, air filter is a new K&N and the plugs are also new.

I'm new to bikes, but where could i find "coils" for the bike? What is a CDI?

You can get ignition coils at any Honda shop but they ain't cheap so you'll want to have yours tested.

A CDI is a type of ignition. It means Capacitive Discharge Ignition. Some folks refer to the CDI module as the "brain box". Those too are also expensive and may not be the problem. If you aren't real familier with working on motorcycles you may want to take it someplace to have it worked on. Your problem although seems simple could be fairly complicated and does require a good bit of specialized equipment to figure out exactly what is wrong. You can just keep throwing parts at it until ya hit the right one but that really gets pricey.

I'm leaning towards something with the carbs though it is tough to tell without the bike sitting in front of me.